Weird electrical problem ruined my car!

[LFY]

The one on the left is my original voltage regulator and the one on the right is the faulty one but it seems to have healthy brushes.






I have been told not to change the brushes because they say by doing this, it will work for a few days and stops working again.

The price of a new alternator is sky high. It would be helpful if there was a way to determine the condition of the voltage regulator before buying. It seems the one I bought is faulty.

[Gibbo2286]

Find a good second hand alternator, yours may have an internal short circuit.

I've never had a new 'faulty' Bosch voltage regulator and I've done maybe hundreds of them.

[white exec]

Complete new alternators on Mister Auto from £60-70 (and a choice of makes).

Looks like there is an ALT FUSE on the car, which (if pulled) would allow the rest of the car to be checked.

This may not be exactly the right diagram, but see item G on it.

[LFY]

I've never had a new 'faulty' Bosch voltage regulator and I've done maybe hundreds of them.

It is a second hand item which I bought. The new original ones are not available in my area.

[white exec]

And your location is....?
[location now inserted into Profile]

[moizeau]

It seems it is fitted to various other makes, here's a Ford Galaxy one
You'll need the official Peugeot part number to cross reference. to be sure.
https://www.piecesauto24.com/ford/galax ... lternateur

[LFY]

And your location is....?

Unfortunately, Iran. Only stock items available here which may or may not work.

[moizeau]

If your item is the same as the first one on the link, click it, scroll down and it gives a list of other cars it's fitted to. More options to source another.

[LFY]

My original alternator is 80 Amp. Is it harmful to use a 120 Amp alternator instead?

[white exec]

No, it should be ok. You might want to check the size of the main output cable between alternator and battery, and increase its size if needed (to avoid any risk of overheating), or run a second cable alongside and in parallel with it.

[LFY]

Today, I managed to disconnect one of connections of the alternator to go for a spin.

First up, I read the codes by Actia and there were " no faults found ".

I started up the engine and immediately checked the battery voltage to make sure alternator is disabled and the voltage was 12.3V and the car was running on the battery alone.

I took the car for a short spin to see how it behaves. Everything was fine and idle was perfect @ 800 RPM. After 15 minutes I pulled over to check the battery voltage again and it was 12.16V which means no charging. I continued driving and about 5 minutes later the idle was again up to 1100 RPM! I pullled over to check the battery voltage and to my surprise the voltage was 16.2V again!! I don't even understand how could this be happened when one of the connections is completely disabled!

Upon seeing the high voltage I immediately shut off the engine and connected my Actia to see if any fault codes have been recorded. These 3 codes were present:




The only conclusion from my experience is that as far as the car was running on battery alone, everything was fine and it performed like before. But the problem (fast idle) started as soon as the voltage increased. How could the alternator charge the battery with one of the wires disconnected? By magic?!

Do these problems happen due to high voltage? I think when the voltage increases the stepper motor confuses and sends wrong signal to the ECU which results in fast idle.

I cleared the fault codes and soon I will remove the intake manifold to get access to the alternator and get ride of that faulty voltage regulator.

[white exec]

There are usually 3 or 4 connections to an alternator:
1 - main (heavy duty) cable out, connecting to Batt+
2 - a +12v permanent live
3 - a +12v switched by IGN switch
4 - maybe (but not always) one more "voltage sensing" connection (to Batt+); sometimes not present.

To prevent the alternator giving any output, it is essential that both #2 and #3 are disconnected, otherwise the alternator could function. Also note that alternators can be partially "self-exciting" and under certain conditions (eg quite high revs) can create enough internal voltage (from residual magnetism) to begin providing an output. Under normal conditions, this doesn't matter at all, but might here . . . which could explain why you were seeing a battery voltage that was 12.something, but then suddenly jumped.

Suggest you disconnect all input cables to the alternator (#2,3,?4) and try another drive.

An alternative test (not easy) might be to leave all the input cables in place, but disconnect the main output cable from the battery, and connect it to another battery instead . . . so the alternator's output is properly loaded with a battery, but not the car's one. Might be difficult to do, and even more so if you want to do a driving test.

Otherwise, as you say, it's alternator out, and repair or exchange.

[EDC5]

The alternator is obviously knackered. I'm not sure if any more tests are required?

I was very interested to hear about the self-exciting effects of alternators and this seems to be a perfect example. Reminds me of a post not so long ago whereby the alternator of the car wouldn't start charging until it was given a few revs.

[white exec]

The reason for wanting to persist with tests was to find out whether the high alternator output voltage had actually damaged any other systems on the car, hence the desire to be able to run the engine without it in circuit.

Agree that the best thing now is probably just to replace (or repair) it. Tests are ok if they're reasonably easily done!

[LFY]

I don't think any more tests are required. Tonight I worked hard for 3 hours to be able to remove that hateful voltage regulator that caused problems.
I managed to remove it with the alternator in its place but I had to open the oil filter to get access to the back side of the alternator. It was really hard! I removed the air intake, throttle body, intake manifold and fuel rail!
Now I want to discard the faulty voltage regulator and use my car's original regulator but with new brushes and see what happens.