Car Broke down! :/ after full revs Any help /advice?

[Bowie69]

In my opinion, it is still very likely that the zener diode blew before any slow blowing car fuse realised what was going on.

[twoqu]

Looks like its an ST BZW 06 19. Thats from what my poor eyesight and magnifying glass can make out. ST was/is the manufacturer. That does seem to correspond to some diode specs.

[newsh]

I guess the diode blowing was the “bang” you mention in your first post?

[twoqu]

Data sheet below.
So it appears to be a transient-voltage-suppression (TVS) diode.

[prj]

He's also saying it should blow the fuse before it blows the diode in the ECU..

Never EVER ask that mechanic for:
1. Any electrical work on your car.
2. Any advice about anything electric.

He's maybe good at wrenching but he knows absolutely nothing about electricity.
Get a genuine alternator before you blow all the control units on your car. ECU is not the only one.

[Bowie69]

Indeed, I'm no auto electrics expert, but do have a degree in electrical/electronic eng, your mechanic doesn't really know what he is saying, unfortunately, just not his skill set, I expect he knows a lot of other stuff instead

[Chris5044]

Never EVER ask that mechanic for:
1. Any electrical work on your car.
2. Any advice about anything electric.

He's maybe good at wrenching but he knows absolutely nothing about electricity.
Get a genuine alternator before you blow all the control units on your car. ECU is not the only one.

Hey thx, he doesnt know that much, which is why he uses other people for electrical things

[LSG]

He could have said what he said hoping you'd go away none the wiser and your problem will be nothing to do with him Honest Mr Chris

[Chris5044]

Ok so news just in .... the mechanic sent the alternator off for testing and it passed for 1.5 hours... and under load ... should I believe this guy or not?

Could this issue be something else with my car?

I'm thinking about getting it tested independantly

[twoqu]

Well what is the mechanics explanation for how the voltage overprotection circuit in the ecu was fried?
Not sure how long you had been driving the car since the new alternator was fitted. Did you see any indication on the gauge perhaps that it was overcharging.
Not aware of any fault with a battery that would cause overvoltage.
It's difficult when you are in the hands of someone else. In hindsight it would have been useful to have documented that fault code had it existed in the ecu. It clearly is not the correct alternator for the vehicle even if someone has got it to fit. You mentioned previously about someone messing around with it at the back which I can only assume was with the wiring. Perhaps this is an issue. Certaintly something to research.

[John.]

Is the pulley the same size as what was on the old alternator, if smaller then at high revs this could be the problem?

[twoqu]

Sorry I misread. Although I am not sure what was retrofited to the alternator unless it was the original pulley!
Does seem possible to use alternative alternators. Perhaps thats what was done to yours.

https://www.s2forum.com/forum/technical/electrical/2007004-a4-b5-alternator-on-audi-rs2?p=2007061#post2007061

[Chris5044]

Hey guys could the ecu have caused this? I spoke to an alternator guy and he said that these cars with the audis the ecu regulates the alternator. So he couldnt test it without the ecu plaugged in etc .. as it is required to regulate it.

My current plan of action:
Get the alternator now surcharged and buy a new bosch alternator and have it made to fit the car or get original one for this car.

Send ecu off for repair and stress test.

Then once its all back the car should then work.. I will then send the whole car to an electrical specialist to test the whole car and that area to make sure it's not something else that is causing this and iron out any gremlins

[Bowie69]

Hey guys could the ecu have caused this? I spoke to an alternator guy and he said that these cars with the audis the ecu regulates the alternator. So he couldnt test it without the ecu plaugged in etc .. as it is required to regulate it.

Cobblers.

You have found someone else that knows nothing. The regulator is on the back of the standard alternator, unless they sold you one without a built in regulator.....????? Which would of course explain your problems, as it would over voltage very quickly indeed.

Much more modern vehicles do indeed use the ECU to regulate the voltage, but we are talking about 40 year old tech here.

Whatever you do, get a STANDARD alternator for your car, no need for anything else at all.

[Chris5044]

Cobbler.

You have found someone else that knows nothing. The regulator is on the back of the standard alternator, unless they sold you one without a built in regulator.....????? Which would of course explain your problems, as it would over voltage very quickly indeed.

Much more modern vehicles do indeed use the ECU to regulate the voltage, but we are talking about 40 year old tech here.

Whatever you do, get a STANDARD alternator for your car, no need for anything else at all.

Hey thank you, but a standard bosch one? hopefully .. as they have left me stuck with an alternator that I cannot give back, as they have drilled it to make it fit my car.. which perhaps isnt right. They said they have tested the alternator at the place that they got it from and it works fine. So I have paid over £200 for parts and labour and have a problem with the car - likely cause the alternator.. they are saying its something with the car.. im still lost...here.. :/

Im basically losing money and feel that they might be taking the piss here.. but they dont know much about electrics...

What can be done?