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Discussion Starter · #1 ·
Hey guys,

It's been a while since I've been on here but looking for some advice.

My daughter has a 2002 Mk2 1.6 and has run into an issue with the car seemingly overcharging the alternator. She broke down a few weeks back and car was taken to a local garage. The alternator and wires had melted and the garage has traced it back to the ECU overcharging the alternator. On my Mk1 the regulator is part of the alternator but it seems that the Mk2 has the regulator as part of the ECU.

So, the garage has sent the ECU off to be repaired, both times it being sent back because the ECU repair company (ECU Doctor/ECU Testing) didn't have the tools to test it? Slightly frustrating as both have said it can be repaired?

Does anyone have any knowledge of how we can/if we can repair the ECU or think of another solve other than buying a new ECU/second hand one and recoding it?

Thanks in advance,

Si
 

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VVT swapped NA & TD04 turbo NB
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Pretty sure mk2 1.8 alternators are self regulating and mk2 1.6 alternators are regulated by ECU no? Or is it just mk1 that aren't self regulated?
Whoops, exactly as you said, mk1 are self regulating, mk2 are ECU regulated.
Sounds to me that if the fault developed randomly that it might have been a short/high resistance somewhere on the circuit.


As for ECU repairs, a swap might be cheaper to be fair but you'd need locks too I imagine unless you're lucky enough to have no immobiliser at all.
Other choice would be an aftermarket ECU like an ME221 but then you would need some road tuning as the basemap will be lumpy especially in winter.
 

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Discussion Starter · #4 ·
Thx guys. Agree an ECU swap may be the answer. The garage spoke to my local Mazda dealership today and they said that if we take another second hand ECU to them they can recode it in about an hr and there would be no need to swap keys, ignition barrels etc. Is this correct? Seems to be too easy?

Failing that the only other option would be to get another ECU, keys, ignition barrel and immobiliser and put all that into her car. Just have have a door key and ignition key.

is there any other part of the car/system that could be causing the overcharging? Or is it really all down to the ECU? Just to add, we’ve put a new alternator, wires and battery on.
 

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VVT swapped NA & TD04 turbo NB
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Thx guys. Agree an ECU swap may be the answer. The garage spoke to my local Mazda dealership today and they said that if we take another second hand ECU to them they can recode it in about an hr and there would be no need to swap keys, ignition barrels etc. Is this correct? Seems to be too easy?

Failing that the only other option would be to get another ECU, keys, ignition barrel and immobiliser and put all that into her car. Just have have a door key and ignition key.

is there any other part of the car/system that could be causing the overcharging? Or is it really all down to the ECU? Just to add, we’ve put a new alternator, wires and battery on.
That is correct but have they told you the cost?
 

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Discussion Starter · #6 ·
So they can recode another second hand ECU? If there is an issue with the actual ECU it’s more than just a recode isn’t it? They said it would be part of the hrs diagnostic charge of £89. Not sure, being a main dealer, they actually know what they’re dealing with. Maybe that’s a bit harsh!

If I’m looking at a second hand ECU, keys, barrels, immobiliser etc they seem to be around £200 plus 1-2hrs labour to fit it all.

Only issue is with a second hand one there’s no real guarantee of it actually working properly in the first place.
 
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