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

[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

[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

[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.

[twoqu]

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

[newsh]

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

[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.

[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]

If its a Zenner diode then at a predermined voltage it will basically short the circuit out, thereby blowing the fuse. The factory manual for the ABY says this is above 16V whilst Dmitri says its 18V. As the voltage should have been regulated at the alternator to 14.5V then there should not have been an issue.
I meant to check if those numbers on the diodes still visible related to the pin assignments of the ecu.

[Bowie69]

Hmm, blowing a fuse which is current based, before the voltage based diode.... well, while voltage and current are inextricably linked, they are not the same, and the chance of voltage getting too high to blow the diode before a fuse blows is pretty high.

Also, fuses are quite slow blow items, typically they can also take around double their rating before going 'pop'. A diode is not so forgiving, and will go pop quite easily once a certain voltage is reached, and very quickly at that.

[Chris5044]

Hey thank you for all the help guys!! I really appreciate this! The mechanic has said he will send the alternator off for testing. He's also saying it should blow the fuse before it blows the diode in the ECU..

Any new thoughts on any of this?

Thx

[twoqu]

I think it would have lost it once battery power was removed from the ecu- it would have been 00532. So once its repaired and connected it will be blank again unfortunately.
Perhaps there is a way of somehow getting the alternator tested off the car and using the findings as a bargaining tool. It would have be independent unless the seller of the alternator is going to put their hands up. Would have thought a new battery would be advisable to add to the list if making a claim, for some leverage.
In hindsight the code would have given a clue/provide evidence but you are way past that now. It does seem the alternator is the main suspect. Even though we know its not the correct fitment, most automotive alterntors use 14V so it should have functioned correctly.

[Chris5044]

******... hmm ok well .. in order to point it at that. If i send the ecu to get repaired .. and the car starts... would the ecu store that over voltage as a fault code? Would it be obvious that the alternator is at fault. I need evidence for this garage.. :/

[Bowie69]

You have found your problem, I think.

Get your old alternator reconditioned by a proper place, then you know it is good for another 200k.

The Chinese 'thing' isn't worth the rusty steel it was made from, and almost certainly the problem here.

Sorry

[twoqu]

Hmmm
Is it me or has the two halves seperated. Looks like its coming apart in the third pic. The Made in China is hardly inspiring!
The stock regulator is 14.5V from what I can tell without knowing what alternator you should have fitted. There is more than one version apparently.
Looks like this is some sort of knock of. I can understand something being remanufactured from the original (Bosch?) alternator by a reputable organisation.
If it has come apart perhaps this has caused some sort of problem with the winding touching the case.
Unfortunately the voltage regulator is on the back of that black case. It is normally secured with two screws.
As we know it takes 18V from the worlds most knowledgable expert on our Motronic ecu's to blow that overvoltage protection, I would contact the vendor of the alternator and see what they have to say about the situation. Assuming its within a warranty period.

[Chris5044]

On dear! You have a nasty Chinese alternator which has probably produced a voltage spike at high revs sufficient to kill your ecu.
i personally would take it back from where it came and explain what damage it has caused and get them to pay to put it right. You can buy a proper OE Bosch remanufactured alternator from a bosch service centre for £200.

is this likely!? :/ i am fuming if it is