MatraSport Forum

Hi there,

I've got a nasty problem: my Murena 2.2 engine doesn't run anymore! A few months ago I had some kind of short circuit (I think), because while waiting for a traffic light the engine suddenly stopped (and all electrics stopped working) and smoke came out of the dashboard. I immediately disconnected the battery and had the car towed to a friend's Peugeot garage. He put the car away and promised to work on it when he had little to do, so that would keep the cost of labour down.

However, he cannot find the cause! :( The cable from the igntion key to the engine was interrupted, but running a new cable didn't solve the problem. When you turn the key, the starter motor runs fine but the ignition won't fire. We think either or both the ignition coil and/or ignition module are broken and then again, we didn't find the cause of the short circuit.

What are the Peugeot replacements of the ignition coil and the ignition modules, if any? Because then we can start replacing them to see if that is the cause. Problem is that Carjoy is on holiday until August 20, so we cannot call Ruud for advice (or spare parts).

Another question: what is the best way to run a bypass electrical cable from front to back? Underneath the car along the handbrake cable, or do you really have to take the interior out to reach for the wiring loom?

Cheers, Robert

(I keep seeing things from the sunny side: the car is due for APK (= Dutch MoT) and it would pass without any problem, if the engine would run that is!)

First Robert you must find the cause of the short, because the last thing you want to do is have a fire and destroy the car.  One common place for an ignition short is where the engine loom crosses from the chassis to the engine.  It can hang down slightly and rub on the alternator adjusting bracket.  If you had a short under the dash, it may have been not directly related to the coil or amplifier feed - simply an ignition circuit supply which caused the whole of the ignition to cut off.  Or it may have burnt the contacts in the ignition switch.

So first find the short - if it was smoking, it must have melted enough to see the damage, then repair as necessary, and make sure the reason for it happening cannot happen again (like something rubbing and wearing through the insulation).

You should not run any by-pass either without finding the short, as you may simply feed the short from the other end, and create the conditions for a fire.

As for the coil and amplifier, it is unlikely that a brief short circuit would damage the coil or cause it to fail.  A short on the ignition side of the coil simply means the coil has earth to both terminals!  How is that going to damage it?  The amplifier could possibly be damaged, but again an earth where there should be 12v is not likely to be a major problem.  If you had 12v where there should be an earth, that could cause the amplifier to burn out.  So you need to know what happened.

To understand why it won't run now, you need to first check all circuits involved and find out if they are all correct.  You obviously need power to the coil and amplifier, and a good earth - which is not always the case as the galvanised chassis can degrade these.  Remove all earths and clean properly.  Then check that you have less than 0.25 ohm resistance between any earth wire and the battery negative pole.  Then you need to check wiring continuity between the distributor and amplifier, and that the distributor is switching.  For the standard Bosch distributor, align the 'fingers' in the distributor, connect a meter to the coil and rotate the 'fingers' back and forth slightly.  You should be able to see the switching effect.  If it is switching, then hold the coil king lead close to the block and rotate back and forth again.  You should get a spark from the lead to the block.

If it won't work and your electrician doesn't know why, I'm afraid he doesn't understand electrics well enough. :-(

Roy

I'm afraid I'll have to AGREE. Electrics is mostly a question about systematically measuring every single connection until you have a positive indication about where the problem is. But to some people, electrics is black magic - they can be excellent mechanics (and perfect freinds ;) ), but still not able make sense of wires and connections.

However, a systematic approach will never fail to find the problem. And here's another bright view on your problem: It's a permanent fault, not something that happens intermittently. My old Espace developed a problem at some point where during acceleration it sometimes cut out completely. I was thinking of sensors, but the car ran well otherwise, so I couldn't do much about it until one day it refused to start in the morning. I put the ignition on and fiddled with connectors and relays until suddently the fuel pump started. It was simply the main power relay to the EFI computer that had come loose in its socket.

Why do you think the ignition module or coil are gone? A short circuit in the ignition module could have caused your problem, theoretically, but Roy is right - replacing either most likely won't help you. You have to find the broken wire first!

- Anders 8)

I'm afraid that bad understanding of electrics is indeed his problem. :( I think I should come to rescue, I am not good at mechanics but in the past I got a degree in electronic engineering, so I should be able to work my way out. ;) First of all, I should locate the root cause, i.e. where the short circuit really happened (if it was a short circuit really), then see how I can get +12V to the ignition circuit (coil, module, solenoid) safely and then I should start suspecting certain parts being faulty, not sooner.

I have one question which may help my way into finding the fault: where exactly does the wiring loom follow the chassis? In other words: how can I reach the wiring loom and take it out? If I'm working on it I could as well replace the whole wiring loom anyway! The car is on a lift, I should be able to reach all parts.

BTW, Roy I read your other response, hope you will be recovering soon :)

Cheers, Robert

You'll be much better at this job then!

The loom to the engine comes out from under the dash on the left side of the front compartment, then goes through a connector on the right side and under the car there to the engine room. It's easy to see once you get under the car. It terminates in a green connector to the upper right of the ignition coil (a bit hard to reach). Before the connector, it's split in two - one going to the engine, the other to the trunk (rear lights).

- Anders

Thanks, Anders! I will also try and replace the connectors then, because I heard they are of very poor quality. My friend the mechanic will probably have sources for automotive cabling and connectors. I think I will leave work early today and talk to that guy, I'm sure he will let me finish the job as he is quite fed up with the problem.

Yes the open type connectors have a tendency to corrode, and the plastic suffers from temperature changes. I try not to touch mine unless I have to.

I've used Vehicle Wiring Products, http://www.vehicle-wiring-products.co.uk/ (http://www.vehicle-wiring-products.co.uk/), they've got it all. But there's a company in the Netherlands too... I don't have the link here with me, but I'll try to find it when I get home. I have also been buying connectors from Conrad Electronic in Germany http://www.conrad.de/ (http://www.conrad.de/), if you can find the stuff you need there, they are far cheaper than VWP.

Got it! "Ripaults" http://www.ripca.com/ (http://www.ripca.com/)

I went to the workshop today and lifted the car up, so I could inspect the wiring from below.

It's worse than I expected...

First the wiring mess around the alternator. Note all the loose wiring and connectors. Is this normal?

(http://www.matramurena.net/pics/wiring-1.jpg)

(http://www.matramurena.net/pics/wiring-2.jpg)

(http://www.matramurena.net/pics/wiring-3.jpg)

(http://www.matramurena.net/pics/wiring-5.jpg)

(http://www.matramurena.net/pics/wiring-10.jpg)

The starter motor looks fine:

(http://www.matramurena.net/pics/wiring-4.jpg)

Then I did a shocking discovery. There is a molten cable under the left front:

(http://www.matramurena.net/pics/wiring-7.jpg)

(http://www.matramurena.net/pics/wiring-9.jpg)

This cable comes from the connector seen in the middle of these pictures. Anyone knows what purpose this cable has?

(http://www.matramurena.net/pics/wiring-11.jpg)

(http://www.matramurena.net/pics/wiring-12.jpg)

Even from above it can be seen that the insulation is gone:

(http://www.matramurena.net/pics/wiring-13.jpg)

Now I really have to consider to replace ALL the unfused wiring.

Two questions:
1. Did some previous owner and/or a Matra "specialist" make a mess of the electrical wiring, or is this kind of electrics "Matra-style"?
2. Is it possible to disconnect the wiring loom without too much cutting, e.g. by disconnecting the cable from the connectors and then make a new cable?

It looks like you have found your problem! Well done!

The wiring in the engine room looks messy and like someone has had to do a crude repair. The original wiring is tape wound all over. There could be a short circuit somewhere back there.

The connector with the melted insulation carries 6 signals, among them the ignition feed to the engine room on pin 6. So the short circuit has burnt that wire.

It looks like you need to make some new wiring; you may be able to fix the engine room wiring and make a new ignition feed, but there could be other problems in the loom if the ignition wire has been very hot. So replacing everything from the three connectors in the front to the rear of the car would be the correct solution.

Some of the wiring in the engine room, however, is buried under the manifold, and the wiring around the ignition module and coil is a bit hard to get at, so if it was me, I think I'd just try to get my car back rolling again by spotting and repairing the short circuit and a parallel ignition feed.

- Anders

That enginebay looks horrible. Get an other engine wiringloom from carjoy.  The connector at the front is for the lights at the front (if i am right). Most off the lights in a murena are UNFUSED. Headlight, foglights, rearlights, interiorlight.....

You can find the wiring diagrams on the website of Laurens
http://www.matramurena.nl/zelfrepareren-elektrischschema.php (http://www.matramurena.nl/zelfrepareren-elektrischschema.php)
Or from Roy

Do they sell original wiringlooms or have the re-made them? I am not very happy with Matra quality if it comes to electrics... Carjoy has tried to work on this mess BTW, the problems really started when they installed a new generator and three weeks later I had a cable fire. I think the whole engine wiring should be replaced. Thanks for the link to the schematics, Bart!

You aren't, Bart ;) The connector to the headlights is out in the well for the popup headlights. The connector with the burnt cable is going to the rear of the car.

No, this number of wires is not original  :o Original electric is very simple in comparison to the other cars, and absolutely doesn't look as chaotic as it does on Your car. I think that somebody who changed Your generator is responsible for Your problem...
But You can also use the engine electric from Tagora 2,2 it is the same.

I know, that was also what Carjoy told me when they installed a new generator, that the previous installation was a mess. They tried to fix it, but I am a bit disappointed they didn't offer me to replace the wiring loom. I don't mind paying 100 Euro more for a repair bill, if it saves me from lots of trouble later :(

Mmmm... the schematics Bart pointed to, are from an early 1.6 (with vacuum warning light instead of choke warning light and a different oil level warning system). It looks like there a fault in the original drawing, too. I can remember Roy said that in the past.

What electrical connections are there in the engine bay? It mustn't be that hard I guess?
Thick wiring (excess of 50A) to:
1. starter motor
2. generator
Thinner wiring to
1. generator (for the dashboard warning light)
2. ignition circuit (coil and module), and a wire to/from the Hall sensor on the flywheel I think?
3. carburettor solenoid (but that one may as well go to the ignition circuit)
4. oil pressure sensor
5. coolant temperature sensor
6. fuel level and low fuel indicator
7. rear window heater relay feed, rear window heater dashboard warning light and the rear window heater itself (*)
and a separate wiring loom to the rear light units. Have I forgotten anything?

Where is the oil level sensor of the 2.2 engine located? Is it the sensor in front of the sump? I noticed a sensor there with one wire broken off...

(*) If the schematics are correct, the rear window heater itself is unfused, only the circuit that feeds the switch, warning light and the relay are protected!

Electrics can take a lot of time, so I doubt if it can be done that cheap ;)


You can't use a diagram for the 1.6, but Lennart has put a reasonably correct 2.2 diagram in the Murena vault on this site:
http://www.matrasport.dk/Cars/Murena/vault/ (http://www.matrasport.dk/Cars/Murena/vault/)

Until you get your handy quality controlled diagram from Roy, this will help you ;)


These two are one fat wire directly to/from the battery. Never fuse this!


Only +12V from the ignition key (circuit 10).


Yes, that's wired to the ignition.


Yes.



These are seperate and not part of the engine wiring loom. Physically they are routed on the fire wall.


Yes: Reversing switch (rear lights) and minus on the ingition coil to drive the rev counter.


Yes, that's probably it.


Oh no, there is a fuse, but the diagram is wrong!

- Anders

I just took a couple of photos of the three connectors from the main loom (under the dash) to the rear of the car, here they are:

This is CC2:
(http://tmp.dinsen.net/murena/cc2.jpg)

This is CC4:
(http://tmp.dinsen.net/murena/cc4.jpg)

And this is CC6, which is the one that carries the ignition circuit (#10):
(http://tmp.dinsen.net/murena/cc6.jpg)

And this is how CC6 looks on my car (mobile phone image):

(http://www.matramurena.net/pics/wiring-8.jpg)

So I think this is the strategy I will follow:
1. Replace connector CC6 in the front.
2. Replace connector MC2 in the engine bay.
3. Replace wire #10 (switched +) throughout the car where necessary (just disconnect it and run a separate cable in parallel)
4. Check wire #1 (permanent +) for damage also
5. Try and clean up the mess around the generator...
6. Remove, clean and re-fit all earthings (110, 110A, 110B, ...)

I am not going to replace wire #10 everywhere, just the part that was hurt by the short circuit 2 years ago, which should have been replaced then!

For the winter, I think I am going to remove the dashboard and replace/repair the wiring inside, since it is quite a mess there as well. Some idiot made a separate switch and ran a separate wire for the windscreen washer instead of finding the fault and leave the original wiring! Also, I am studying on a new fuse board, because that is a source of trouble on all Murenas. There are many things I don't understand that are left out (well, of course I understand: cost cutting), e.g. a relay switching the #10 wire instead of the ignition key, leaving the headlights unfused, etc.

After this operation is complete, I think I am quite near becoming a Matra Murena electrics guru ;)

Cheers, Robert.

Hi Robert

Yes, that's corrosion. It happens when a large constant current flows in an electric circuit and moisture gets into the housing. It's working the reverse of a battery, so to speak. When the connectors then start corroding, the resistance increases and heat builds up. That's why the housing is slightly burnt. The best way to prevent it is to clean and grease the connectors well.

I haven't found connector mouldings that fit in the original cutouts. The original male connectors have some very nice tabs that fit into the cutouts, but if the old mouldings are okay, it's quite easy to replace the terminals with new ones. This will preserve the original look. The rubber around the connectors doesn't help much, in my opinion it's better to leave them open, but the grease the whole connector inside and outside before putting them together.

(http://www.vehicle-wiring-products.eu/VWP-onlinestore/terminalsnonins/photo/Fbl6.jpg)
These are available at VWP in both male and female types and they fit directly into the old mouldings: http://www.vehicle-wiring-products.eu/VWP-onlinestore/terminalsnonins/noninsblades.php (http://www.vehicle-wiring-products.eu/VWP-onlinestore/terminalsnonins/noninsblades.php).

About the ignition lock: It is designed to switch a very large current, so if everything is okay, I don't see the advantage of fitting a relay instead. The windows are switched by a relay, however, probably because their current consumption exceeds the maximum allowable over the lock. That said, however, I will fit a 70A relay on my Murena since I've had some problems with the connections to the ignition lock getting very hot and melting. I'm going to fit a new ignition circuit directly from the battery over a high current fuse to the relay, and fit the relay under the dash. I will also fit a few new fuses for radio and auxillary power outlet for my mobile phone and GPS. My radio is in need of a better power supply, so that will help there too.

Fuses are good and bad. Reliability wise, they introduce an additonal potetially weak link. But they are excellent fault finding tools.

I "fell in love" with this modular unit some time ago, but recently it has moved down my wish list as the old fuse board works well enough as it is. After all, it only powers "uncritical" consumers. Parts are also available from VWP, but the product is from Ripaults AFAIK.
(http://www.vehicle-wiring-products.eu/VWP-onlinestore/relays/photo/1520demo.jpg)

- Anders 8)

Every carpart store are selling these. I'm sure that peugeot garage has them aswell.


Héy, That's a great thing! I want 1 of those! It is added to my "hundred things to do" list ;)

http://www.vehicle-wiring-products.eu/VWP-onlinestore/relays/sockets.php#box (http://www.vehicle-wiring-products.eu/VWP-onlinestore/relays/sockets.php#box)

EDIT

Just spotted this:

(http://www.vehicle-wiring-products.eu/VWP-onlinestore/relays/photo/r30af.jpg)
http://www.vehicle-wiring-products.eu/VWP-onlinestore/relays/relays.php (http://www.vehicle-wiring-products.eu/VWP-onlinestore/relays/relays.php)

This must be a major step forward in fusing the headlight circuits. FJust replace the relais by this one and there is your fuse!

Not this time (corrosion), because it was a short circuit that made current flow through the #10 wire and thus melting the connector. I am not re-using this one, it's too far gone. But the connectors are of such poor quality, that replacing or at least cleaning/greasing them is a good idea anyway.

Please careful if you use these diagrams (1.6 and 2.2) as there are many mistakes in them.


The official workshop manual wiring diagrams had mistakes in them; someone copied them and made those crude diagrams AND added more mistakes, and someone put some diagrams on a CD which Delcourt once sold, and there are even more mistakes on those!

This was why I spent many hours making my own Murena wiring diagrams which also cover most variations.  Did you know for instance that the first 1.6 Murena models had the instruments lit all the time the ignition was on (like the Bagheera)?  They are not switched on when you switch the sidelamps on, which is why you have a sidelight warning light in the instrument panel.  You need it to know when the lights are on, because the instrument lights being on mean nothing concerning outside lights unlike a normal system.

There are variations not only between 1.6 and 2.2 but between early and late cars, normal French spec. and German spec. owing to different laws in those countries, and the original diagrams lack much information about the real looms.  Where is the 82 ohm resistor for instance and why is it there?  My diagrams include all the information and they are accurate.  They are obviously only as standard so if your car has had alterations or additions, then you should keep notes of these, or whoever did the modifications should have made them.  Unfortunately, often that never happens which leads to problems with the subsequent owners!

At least the Murena is quite a simple car, and the wiring is easy to work out if you know electrics.

Roy

My company car (Astra) and my girlfriend's Citroën C3 have the same "feature", the instrument lights switch on with the ignition and there is a green indicator light when the sidelamps have been switched on. So it's not only the early Murena :)
Unfortunately, the people who worked on my car (even a "Matra specialist") didn't know **** about electrics. Today, I worked hours on my car's electrical system, to repair the short circuit and the bad connections, which kept the engine from running. I have to admit: it is a very simple car to work on, once you have the car on a lift.

First I started measuring voltages at the diagnostic connector on top of the engine. I bypassed the ignition switch and connected the #10 wire after the "CC6" connector under the front hood. The voltage from the #3 wire was 11,8V (the battery was heavily drained during the two months standstill as I noticed later), but the voltage from the #10 wire was only 10,8V, so there was a 1V voltage drop!

I raised the car on a lift and took a look at the "MC2" connector in the engine bay. I took the male and female parts of the connectors apart and... one of the connectors literally fell apart! I turned out that a very crude repair has been done to the lower part of the connector (the one that goes to the front of the car) and that the wiring loom there has been left untouched after the first short circuit, two years ago. The #10 wire which was coming from the main wiring loom was almost "naked" and heavily corroded. This can only be seen from below, but it was clearly a time bomb!

If I am correct, through this MC2 connector are the following leads running:
#94 temperature sensor
#90 oil pressure sensor
#15 tacho signal
#10 switched +12V from the ignition key
#14 switched +12V from the ignition key in the "start" position
#9 charging indicator

I ran a bypass #10 cable along the main wiring loom, from the ignition switch to the engine wiring loom. Also, I connected the #9 and #14 from the engine wiring loom to the original main engine loom. Then I tried to start the engine and it did fire once, before the battery went dead :-[ So I charged the battery a bit and after half an hour I tried to start the engine again: VRROUMMMMM!!!! Yee-haaa!!! The engine is running again!

Now I have to complete the task. First, the battery charging light is still not working (and the bulb isn't broken), so I think I will directly connect the #9 wire to the generator, instead of having it running around the wiring loom. Second, I have to find a decent way to re-fit all the other wiring going through those half molten connectors. And, of course. clean up the wiring mess around the generator.

But I am confident I will bring this task to a succesful end :)

I am sure you will Robert, but be careful with the charging system.  You must not bypass the 82 ohm resistor.  It is necessary for the charging system to work correctly.  An alternator must have a certain current to initally energise.  Once charging they self energise.  The warning light used to be large enough to provide this current, but with the newer smaller bulb that the Bagheera and Murena uses it is no longer enough.  So Matra used a resistor in parallel to the bulb to provide the total current.

Your list for the MC2 connector is correct.

Roy

Where is that 82 ohm resistor located Roy? Is it in the instrument panel, or is it fitted somewhere near the alternator? I can't seem to find it on the schematics, but this may just be one of the many faults in them ;)

Cheers,

Robert

Yes, this is another of the problems with the original diagrams.

Look carefully at the plug on the back of the instrument panel.

Roy

OK, then there is no problem, since I am only re-routing the cable up till and including the connector under the front hood. The rest of the #9 cable seems fine. I should be able to check whether the cable is good, since switching on the ignition without starting the engine should give a positive voltage to the #9 terminal.

Is the 82 ohm resistor inside the plug (i.e. combined with the light bulb) or is it part of the printed circuit? I have swapped some of the light bulbs to check whether the light was gone just because the bulb was broken.

No it's on the plug itself.

Roy, woult you think the resistor is necessary in parallel with the bulb to get the alternator regulator started, or is it to ensure that it can start even if the bulb blows?

Robert, In case the wiring is broken to the alternator, you will get charging problems. Just a thought... maybe you had the alternator replaced only because of bad wiring and not because of a problem in it?

I think newer regulators are able to start even without the charge warning light not wired.

Hmmm...

- when I bought the car, the warning light wasn't working, I never bothered to repair
- the first year I had to replace the battery, after half a year I had to replace the battery again
- three years later the alternator has been replaced because I was told it wasn't charging well
- the charging light worked fine after that
- three weeks later a short circuit almost set fire to my car, it was repaired under warranty
- two years later, just before the second short circuit, the charging warning light quit again

I will check the resistance tomorrow with a digital multimeter, if it reads somewhere around 82 ohm (give or take 10%) it must be OK.

Hmm your story just indicates "problems"... nothing like what I thought.


I think the bulb is 1.5W, i.e. about the same resistance as the resistor, and as they are wired in parallel you should get some 30-50 Ohm on your multimeter if you are measuring from the alternator.

I am confident now that many mechanics don't know **** about electrics and electronics. And that includes those who work on Murena's for living.

Speaking of problems, there is an oil leak coming from the top of the engine, between the 1st and 2nd cylinder. Those are signs of the cylinder head gasket starting to fail, a mechanic told me :( Also, I am not really happy with the state the rubber hoses of the cooling system are in.

What are the signs? Coolant in the oil? Oil in the coolant? What is the state of the spark plugs in these cylinders?

If it's on the back (exhaust side) of the engine, then check the rocker cover gasket: If the oil is also above the head gasket, then that's probably the source. It can leak, and if it fails the leak can be quite dramatic. The fix is easy though! I had this problem exactly one year ago (Lennart, Roy will remember ;) )

No, the bulb is 1.2 watts.  The 82 ohm resisitor is roughly equivalent to the 2.2 watt bulb manufacturers always used to use for insturment warning lamps.  (if you use 13.4 volts which is minimum charging voltage and since R=V squared/W  the resistance is 81.62 ohm)  Now it could be that they designed this to energise the alternator if the bulb was blown as you suggested, but I don't see why they would do this since no other manufacturer has ever done this to my knowledge and with the bulb blown you have no quick or visual indication of any problem.  The real reason will probably never be known unless you could find the person who designed it and asked them!

Since the bulb should always be in balance with the system charging, the same voltage one side (from the battery) as the other (the alternator) if the bulb glows it shows there is no longer a balance and one side is higher than the other, causing a current flow.  If it is the alternator which is higher it signifies over-charging, something people often forget - they always tend to assume the light on means under-charging.  Now as the Murena battery condition gauge reads low, if it was slightly over-charging the gauge could be a little higher than usual but you might not realise you had a problem if you had no bulb.  So putting a resistor in to allow the system to run without a bulb is a bad idea.  Over-charging damages the battery and often electronic components.

Also, when I investigated a Bagheera that wasn't charging correctly, the only problem turned out to be the bulb was missing!  As soon as I replaced the bulb, it charged correctly, suggesting that it required both to energise correctly.

The bulb and resistor in parallel should give you roughly 49 - 50 ohms at 12 volts

Self energising alternators require nine diodes as opposed to six for normal ignition energised alternators.  More importantly if you used a self energising alternator, you would need a means to switch off the supply when the engine was off otherwise the current drain through the alternator would drain your battery, and you would need a separate warning light control unit.  We used to use these 3AW (warning light control) units years ago on BMC vehicles when we did use self energising alternators!  I can't think of any cars with self energising units today.

Roy

I have done some measurements yesterday.
When the ignition is switched off, the ignition warning light circuit reads about 30 ohm between #9 wire and chassis ground.
If I switch the ignition on and connect the igntion warning light to ground, the warning light goes on. But it doesn't come on once I connect the #9 to the wire which should be the #9 wire.

What is the grey wire with red connector seen in this picture. Is that the #9 wire (charging warning light)?
(http://www.matramurena.net/pics/wiring-1.jpg)

According to the schematics at http://www.matrasport.dk/vault/Murena/murena_el_diagram_2of2.jpg (http://www.matrasport.dk/vault/Murena/murena_el_diagram_2of2.jpg), there are 4 connections to the alternator:
#1: permanent +12V from battery
#8: goes to diagnostic connector, can't seem to find another purpose
#9: charging warning light
#10: switched +12V from ignition key

I am confused, I can only find the permanent +12V and that grey wire...

No an original grey wire with red marker is a permanent ignition wire (No.10)
(The problem is with your altered wiring you cannot rely on anything.  You may have to check where every one actually goes)
The warning light wire should be red with green marker (No.9)
The red wire with yellow marker goes to the diagnostic socket (No.8)
Large red wires are live to battery/starter (No.1)
And there should be a black earth wire (110C)

You might also have a radio suppressor which would be bolted to the earth point with a small wire connected to the live connection (1).


You need to find out what they have done with the red wire with green marker (9).  Someone might have removed the end, and lost the green marker and assumed as it is red that it is the same as the live wires.  It is not.  The same applies to the red wire with yellow marker that only goes to the diagnostic socket.  Separate all red wires and check them individually.

From your photo it looks like you have no wire connected to the warning light connection.  The connection is the second small connector in the socket where your grey wire is connected.  There should have been a plug on the loom with two wires in it, to connect in to that socket and the other terminal slightly below your grey wire, is the warning light connection.

Roy

OK, I will do that! This might explain why there are a couple of loose connectors hanging around.
Could it have done damage to the alternator if I have accidentally swapped the wires in that socket, i.e. the #10 to the warning light connection?

By the way, what purpose has the #8 wire to the diagnostic socket? The #1 and #10 wires are also present there, so it must be something else... And if the #9 and #10 wires go to that small socket mentioned earlier, where should the #8 go?

And is it a good idea if I run the #9 directly to the alternator, instead of through the engine wiring loom (which I do not trust)

Thanks again for your help, Roy!

It's there to diagnose faults on the alternator itself, specifically the regulator. It's all described in the workshop manual, but requires a bit of electronics knowledge. You can easily live without it.



It shouldn't make any difference if you can ensure there is a connection and there are no short circuits. If you don't trust the loom, I suggest you take it out of the car completely and restore it. Getting it free of the tabs under the inlet manifold is a bit difficult as far as I can see though, unless you unscrew the manifold from the head of course. But maybe it is possible to do that without detaching the coolant hoses, though it may be necessary to take the carburettor off. What do you think, Roy?

- Anders

Yes, I wondered about those.


Not sure, but if you think that the warning light wire would have no voltage only current, since the bulb will have taken the voltage; whilst the ignition wire will have full voltage, there is a possibility.


As Anders has pointed out, it is purely for diagnostics, so if you never use it then it is not important if you don't have it connected.


It attaches to the main red terminal (No.1)


Yes, you can run it directly, just as long as it is not going to get trapped, or caught or rubbed through by anything.  Getting the engine loom out without stripping is always difficult.  The standard down-draught carb. manifold should have a support bolted to the bottom of it, going to the block.  This is difficult to get at and makes the manifold difficult to remove, as it is not only bolted to the head.  However, ideally it would be best to remove and remake the engine loom, but you have to weigh up the work against the need, and risk.

Roy

The good news: I managed to get the engine working and the alternator is charging, with a functioning warning light! (that is, it goes black when the engine is running and lights up when the engine is not running) The car passed the APK (MoT) flawlessly and it should be ready to roll.

However, I had some things to finish.

The bad news: while I was busy replacing the #10 wire behind the dashboard (if I'm correct, the ignition switched battery voltage goes to the engine, to the fuse board and to the interior fan), I did yet another horrible discovery. The +12V connector and the connector to the second position (the one I'm using most of the time) were completely rotten, the latter literally fell apart when I was trying to pull it off the switch!

Ceci n'est pas un commutateur...
(http://www.matramurena.net/pics/fanswitch1.jpg)

c'est un art du bruler!
(http://www.matramurena.net/pics/fanswitch2.jpg)

Well, at least I know where the smoke came from when my car died two months ago! I hope I can find some kind of replacement, there is an old electronic parts store in town here (the last of the Mohicans), or else I should source one from Carjoy or Simon, because this one is too far gone I'm afraid.

What fuse shall I use to protect the fan switch circuitry? Will 20A suffice?

Been there, done that:
http://www.matrasport.dk/Cars/Murena/Stories/fanswitch/index.html

You'll notice my switch looks very similar.

Years ago my car had a leaky sunroof, which often caused the interior to become damp, and I assumed this humidity accelerated the deterioration of various things - including the connectirs on the switch. But the main reason is probably that it per design gets warm when the fan is on (which it normally always has to be). So after 20 years of warming up/cooling down, the corrosion has easy play.


dunno, - I replaced the switch with a new one from MatraMagic, and it hardly gets warm at all, so I haven't thought about fitting a fuse. I don't think my melting switch was pulling more amps than usual, - it was just being burned off in the switch instead of the fan motor.

Having said that, it still might be a good idea, and considering the not-so-impressive power of the fan, I'd think 20-30A should suffice. 

/Lennart

Hoooray!! Very good news, indeed.

About the fan switch... I'm about the fuse that myself as soon as I get a spare evening to fit the ignition relay I have complete with harness lying on my workshop table... I'm going to try a 15A fuse. I'm sure that is enough, after all it is a relaitvely small fan.

A switch on an inductive load (like a motor) is bound to give problems in the long run, but you can hope that the run is very long. However, as long as it works, the problem isn't great, the problem comes when the contacts get so dirty that they give a resistance - the switch will then get hot as current is drawn through it.

The solution to the problem is to fit a diode in reverse over the switch. That will short circuit the induced current instead of creating sparks inside the switch.

Lennart, how did you get the knobs off the heater control?
(http://www.matrasport.dk/Cars/Murena/Stories/fanswitch/Med/dsc_7597.jpg)

I had the heater problem only a month or two ago... good thing you discovered it before it caught fire..... My first warning that something was wrong, was when smoke came pouring out from behind the dashboard ..!  :o

I have a 10 amp fuse in the pre-heater feeding the fan. It works, so 10 amp will do.

But beware. fusing things is no guarantee for safe electrical system. Example: The fan is now fused with 10 amps. So if the fan circuit takes more than 10 amps, fuse blow, everybody happy. But what happened to brinkie and krede is a bad connection on the switch. This is not a short or overload circuit! If this bad connection has a resistance of 0.1 ohm, and the fan takes 10 amp, than the power it generates in this bad connection is 10 watt!
10 watt doesn't sound as a lot but 10 watt can generate enough heat to melt things or worse.

(yes, electricity is my hobby and occupation) ;)

Just pull

I did. Didn't help :(

I usually follow a more theoretical approach :P

P = U * I, where U is the battery voltage of 13,8V and I the maximum current of 10A, which brings the theoretical maximum power dissipation to 138W.

So there can easily be 100W of heat being dissipated, which is well enough to burn a hole in the dashboard, or burn up most of the plastic isolation and generate nice smoke :)

Still, fusing of the heater fan circuit sounds like a good idea to me. While busy doing that, I could as well make new connections to the radio and the auxilary power connector (where the cigarette lighter used to be, but I'm a non-smoker)

This 138 watt is power used by the fan to spin around and move air. The 10 watt burning in the bad connection is calcutated as follow: U=I/R = 10amp/0,1ohm = 1volt. P=UxI = 1voltx10amp =10 watt.  (or P=Isquare/R) :P
Don't get me wrong. I don't say that extra fuse is a waste. Only it does not prevent burnt switches. But it does prevent worse if this excessive heat is melting other wires and cause short circuits.  Making extra fuses is on my "100 things to do" list too ;)

The 3 plastic heater slide knobs are held by a 'pin' on the metal arm locking into a hole in the plastic.  Actually it is not a very deep pin, but if the knobs are tight, as they should be, you need to open the knobs up slightly to pull them off.  Some will simply pull off as they are either loose, already spread open or damaged.  To open the back up is obviously difficult without the right tool, as you need to come back towards you with a fine tool poked through the heater slide holes.  We mechanics have what are called 'pick' sets.  These are small like a screwdriver, but the ends are pointed.  The ends are variously shaped, but they have straight, 90 degree, 135 degree, etc.  If you poke one with the point coming back at you into the back of the knob on the underside of the metal arm, and open it up slightly, it will pull off.  If you don't open up a tight fitting knob, something will usually break!

If you have a knob off and you look inside the rectangular fitting hole, you will see a ramp moulded in the plastic so that as you push it on, it automatically opens up and slides over the pin, and then springs back down and locks it on.

The fan knob just pulls off, being a tight push fit with a 'D' shape for correct location.

As for the topic of extra fuses, just bear in mind that for every fuse you add at least four extra connection points, and no connection is perfect so you actually increase the circuit resistance as well as giving it more potential trouble points.  You need to weigh the costs against the benefits in all respects.

Roy

 ;)The best time to do this is 10 past 5 ;)

Thank you, Roy, that was just the information I needed :)

I did notice that it looked like there was some kind of lock from looking at the knobs from the underside, but I couldn't figure out how to disengage it. I will see if I can construct a suitable tool to extract the knobs without damaging them. I don't have any idea right now, but I'll probably be able to come up with something...


Absolutely, and stand on one leg and say "koochachoo"? :D

- Anders

If you pull it will come off but i found you may damage the plastic, the plastic fits very tighly on to a metal shaft with a domed end, this ripped the plastic making it very easy to pull off in future but less than sturdy when re-fitted. Good luck coz they take some pulling. Are these switches still obtainable, and for that matter the black plastic sliding switches? looking at mine it will need doing sooner rather than later.

I found mine were quite easy to pull off (with care), even when I got the car back in 1995 - they have probably been forced off by a previous  owner. The plastic isn't broken, but the hole may have been opened up a bit.

/Lennart

Well, finally, I've got my car back on the road! There are still a couple of things to fix, but at least she's running again and has been parked proudly in front of the house.

The issues I have to work on are:

• Bad idling, especially when the headlights are up and the interior fan is at full speed
• Interior heater gives warm air even when set to cold
• The driver's seat fabric is getting loose

The first problem is either a vacuum leak or another electrical problem (both can be fixed with some searching I guess). The second one is described in Roy's FAQ so I have to unscrew the cover again and start working on that; the last problem will be fixed when I finally will decide to put leather seats in (which is constantly delayed as more urgent problems keep on popping up)

But in all those months I have been missing the car, I did almost forget what fun it is to drive a Murena. Especially when I got used to my girlfriend's shopping cart (a C3 with 68 bhp Diesel engine). She doesn't like the Murena but that's entirely her problem ;)

Excellent news!
If its only a small amount, you might get around it by adjusting the other end of the cable
(from the bonnet side of things)

Same here, - when I bought my car in 1995, the drivers seat was torn as the previous owner was so short he had the seat far forward, so the seatbelt rubbed against the seat. Now, 12 years down the line, i STILL haven't got new seats,  BUT they are finally on order (!).


Been there, done that. Several times during my 12 years of ownership actually - and had the same revelation when I finally got the car on the road again.

Happy driving !

/Lennart