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Author Topic: Alternator trouble  (Read 9046 times)
madeinfrance
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« on: September 15, 2010, 01:49:11 pm »

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?
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roy4matra
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« Reply #1 on: September 15, 2010, 03:40:23 pm »

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...

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
« Last Edit: September 15, 2010, 03:45:24 pm by roy4matra » Logged

madeinfrance
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« Reply #2 on: September 15, 2010, 03:50:43 pm »

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.
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suffolkpete
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« Reply #3 on: September 15, 2010, 08:49:36 pm »

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.
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Oetker
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« Reply #4 on: September 15, 2010, 11:19:05 pm »

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.

The bulb goes out when the engine is running.
In fact you replace the circuit that goes to the front with this bulb.
« Last Edit: September 15, 2010, 11:26:23 pm by Oetker » Logged

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Murena 2.2 Red 1982. Murena 1.6 black on places.
madeinfrance
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« Reply #5 on: September 16, 2010, 11:39:51 pm »

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.
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Oetker
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« Reply #6 on: September 16, 2010, 11:53:52 pm »

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.
« Last Edit: September 17, 2010, 12:01:55 am by Oetker » Logged

I feel like Jonah, only my fish looks different.
Murena 2.2 Red 1982. Murena 1.6 black on places.
roy4matra
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« Reply #7 on: September 20, 2010, 10:42:50 am »

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.

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.

Quote
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.

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
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michaltalbot
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« Reply #8 on: September 20, 2010, 09:47:53 pm »

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

1,-Eur = 25,- CZK it means cca 110,-Eur for new complete alternator.
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madeinfrance
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« Reply #9 on: September 21, 2010, 11:36:38 pm »


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.


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?
Should any be mounted to the bottom connectors?
On the picture below the connectors are at the top.
« Last Edit: September 21, 2010, 11:39:01 pm by madeinfrance » Logged

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madeinfrance
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« Reply #10 on: September 21, 2010, 11:53:28 pm »

This image shows better that a red wire shoe is sitting on one connector without the wire connected anymore.
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michaltalbot
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« Reply #11 on: September 21, 2010, 11:53:45 pm »

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.
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madeinfrance
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« Reply #12 on: September 21, 2010, 11:55:19 pm »

Yes, I just posted a picture showing a wire shoe still sitting on the connector. You meen probably both wires shoud be connected there?
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michaltalbot
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« Reply #13 on: September 22, 2010, 12:00:28 am »

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...
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Jon Weywadt
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« Reply #14 on: September 22, 2010, 08:49:58 am »

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