MatraSport Forum

I am having trouble with the charge voltage in my Murena. There is some charge, but not much. At idle without any elctrics on the voltage is 13,0 V. (While the brand new battery was 12,5V when installed). It is drivable, and probably charging a tiny bit, but not if driving with the heater or wipers on etc. The old battery got discharged one day when driving in rain. On the other hand I drove a 600km trip without trouble the day before that, but only used front and headlights. What would be the typicaly failure? Broken Alternator or just som loose / bad wiring?

13.0 volts is NOT charging.  Charging voltage is always 13.4 to 14.4 volts with an alternator.  So your alternator has failed.  It's probably the regulator but you need to check the system out (or have it checked for you) since it could be an open circuit (wire broken or almost broken, maybe a strand or two still hanging on!).  If the battery is not good, you need to put a good one on to do the checks otherwise you can get a false result.  i.e. A poor battery could be holding the charging voltage down.

A battery is 6 cells of 2.2 volts max. giving a theoretical 13.2 volts max. which is why the charging voltage starts above this at 13.4 volts.  A battery can be fully charged one moment but if one cell has a short or failure the charge can disappear in minutes or under a heavy load such as trying to start the engine or use headlamps etc.

Roy

Thank you for your answer. I thougth there was some charge to the battery since the Voltage is higher (13,0) with the engine running than without (12,5). The battery is brand new.  I will start with checking the wires.

At the risk of stating the obvious, is the drive belt at the correct tension?  I don't believe the test you've done is a good test anyway, as the alternator will not be producing its full output at idling speed.  A rule of thumb that has stood me in good stead over the years is to run the engine at about 2000 rpm and turn the headlights on.  If you can see a voltage within the range that Roy has quoted, then the alternator is probably ok.  One of the joys of Murena ownership is the plague of electrical gremlins that can occur due to the poor quality of the connectors used.  I have been caught out in the past by the connector that carries some of the connections from the front to the engine bay, situated on the left of the car near the fuse panel.  This carries the connection from the alternator to the warning light.  A disconnection here and the alternator stops charging and the light will not light to alert you to the fact.  Does it come on when you turn the ignition on and go out when you start the engine?  Check all connections thoroughly, including the edge connectors on the fuse panel before condemning the alternator.

Also the connector at the right side of the enginebay fooled me once.
The same wire red/black from the connector that suffolkpete described goes there, and had a bad connection.
You can easily check if the or alternator is at fault.
Take the connector on the alternator out .
Get a bulb 12 Volt 3.5 Watt (NB: or something near that)
Connect it from B+ (the thick red wire) to L on the alternator.
Measure Voltage on the battery at 1500-2000 RPM.
It has to be around 13.4 Volt.
If it is much lower probably the alternator is at fault.
(http://img337.imageshack.us/img337/4329/lading1001vs8.jpg)
The bulb goes out when the engine is running.
In fact you replace the circuit that goes to the front with this bulb.

I havent had the time to sort out the problem, but I have done a quick check. The charge warning light is not working when turning the ignition. Reving to 2000-3000 rpm has no effect on the voltage either. And I have found two loose wires close to the alternator in the engine bay. One red and one grey one I think. I must have a closer look to find out what their purpose is. However the car is still running ok and all electrics is working.

Do the test I described and you know if it is the alternator or the bulb circuit.
That bulb circuit needs to be O.K to let the alternator work.
It gives the center coil in the alternator the needed voltage to do his job.
Only L connection needs to be connected to let the alternator work.
The other thin wires are not needed.
They are going to the test connector.

There is the first problem since the alternator energises through the warning light and resistor.  So if it is not coming on, either there is an open circuit, or a fault in the regulator.


If you have a grey one not connected that may be the problem.  Grey is an ignition wire, and unusually the 2.2 Murena alternator needs an ignition feed as well as the normal positive, negative, and warning light wiring.  I'm assuming you have the standard Paris-Rhone A13N10 alternator.

As with all electrics, first have the correct wiring diagram, understand the system, and you can then check the connections and system.  Note: even the official wiring diagram has mistakes or things left out.  That was why I made mine - to include everything and be accurate.

Roy

What do you think about this: http://www.automatejcek.cz/nahradni-dily/autodily/alternator/A9152B/ (http://www.automatejcek.cz/nahradni-dily/autodily/alternator/A9152B/)

1,-Eur = 25,- CZK it means cca 110,-Eur for new complete alternator.

I definitly got one grey loose wire, and one red. Both is thin and seen in the right of the image. Also the alternator is probably missing some wires? (http://farm5.static.flickr.com/4083/5012430367_5972a04403_z.jpg)
Should any be mounted to the bottom connectors?
On the picture below the connectors are at the top.
(http://www.automatejcek.cz/picts/eshop/nahradni-dily/TCD201001/621/A9152B_2.jpg)

This image shows better that a red wire shoe is sitting on one connector without the wire connected anymore.
(http://farm5.static.flickr.com/4145/5012483041_99a8f371e9_z.jpg)

I think that they have to be connected to the double connector on the regulator. On Your picture of the single alternator it is on its upper side.

Yes, I just posted a picture showing a wire shoe still sitting on the connector. You meen probably both wires shoud be connected there?

There are two connectors and You have two wires - each one wire to each one connector. Originaly red + grey wires are in plastic connector which have special shape to fit right into the regulator. This regulator is saying to the alternator when batery is fully loaded to make less of power than when batery is empty. Sorry for my English...

Both wires need to be connected. The grey wire goes to pin "10" on the Alternator. It feeds power from the ignition switch to the coils in the Alternator. If it is broken the alternator will not charge the battery. Pin 9 provides ground for the power to the ignition light. when the engine is running it has 12V+ on it, thus turning off the ignition light.

You can still start the car and drive as long as there is enough charge on the battery. But at one point it will not be enough to crank the car and deliver a spark.

I found that out while troubleshooting the problem that my charge light does not come on when I turn the ignition key. I had swapped the two wires on electronic module on the alternator (pins 9 and 10) It didn't solve it and I forgot to swap them back, with the result that after a week of driving, the car would not start and the battery was low. Swapped back and it charges fine. (But it still won't turn on the charge light. >:( Bulb and resistor is OK on the instrument panel, but the wire from pin 9 to the bulb must be broken. It is a low priority item, so it is still not fixed. ;) )

When wire 9 is broken, no charge will take place.
It's going to the center coil of the alternator giving the bulb minus trough the coil.
If the alternator runs, this coil will give + on L and then the bulb goes off, getting plus contact and plus from the center coil.
You can get various results depending what alternator is fitted and what regulator module.

Working on the car now. My alternator only got one connector at the bottom it shows. (the red disconnected wire shoe.) and it says Valeo. This means it is not the original one?

Tried connecting the grey wire to the connector. Jumpstarted the car and now got a more healthy 13,6 V when idling. Tested the car on a small trip, and even think the engine runs better than before. Quicker throttle response and bottom acceleration. Maybe just a mind trick but anyway - New problem: The engine cant be turned off now. Even disconnecting the battery did not help. Had to remove the grey wire before it died. The alternator may be fine then, but how should it be connected..   ::)

Picture with the grey wire connected to the only connector available.
(http://farm5.static.flickr.com/4092/5015932794_069025515c.jpg)

Then the grey wire has to go to the other contact in the connector, but I don't see that contact in there ???.
You puted + contact on the place the L wire needs to go.
The L wire is normaly red/black or red.
The way you connected this ,the bulb on the dash will not work and the car will not stop after the key is switched to off position..
If you have only 1 contact in there, it is not the original alternator.
In that case this contact = +D and has to go to the bulb.

I only got one. You meen that the grey wire should not go there  but the red? I did not get a charge light with the grey btw.

The grey wire is + contact and should not go there.
From the bulb goes a red/black wire to the connector located right in the engine bay.
That wire should go there.
I rewired the engine bay and found the wire on the connector red/black.
After the connector I changed it to red.
In my case it was original colors that way, but I found out different colors are used in some Murena's.
(http://img215.imageshack.us/img215/4479/p1020716medium.jpg)

Now I have attached the other (red) wire to the alternator. The result is a working charge light. It is on when turning the ignition on, but goes of when the engine starts. The idling voltages is however only 13.2 - 13,3 V. Switching the lights on, and it drops to 13,0. (better than without any wires connected but lower than with the grey.) How should the battery-display in the dashboard work? It is still left on the "-" side. Could the charge voltage be improved with new battery connections? The ones on the battery is not in particular good condition I think. 

I think the alternator is working more or less correct if charging light goes completely off.
You have to measure the voltage at the battery with around 2000 rpm.
The charge indicator gauge is a bit of a strange instrument.
It works with a bi-metal and react slow.
You can learn to liv with it or get the instrument about correct by adjusting it.

With this nut you can adjust the gauge.
(http://a.imageshack.us/img404/3607/laadstrmeter2.jpg)

Put on a voltage of 14.4 volt and adjust to this level.
(http://a.imageshack.us/img831/9663/laadstrmeter1.jpg)