ECU problems

[Pav2222]

Hi

My Mercedes mechanic has told me the ECU is done on my 1992 500E.

Any ideas where to source another one? I’ve read the 400E shares the same ECU?

Same issues with the emissions/catalytic converters.

Any help would be greatly appreciated.

Thanks

 

[gsxr]

What is wrong with the ECU? They rarely fail completely. Usually, replacing the 6-7 electrolytic capacitors is all that's needed. The 400E ECU is not the same. You can probably find one on eBay but plan on replacing the capacitors proactively. The 1990-1992 LH modules used capacitors which seem to have a shorter lifespan than the caps used on later modules (something we're just learning as these units pass 30 years old). I have one available, details here. You can get a used one for less and then replace the capacitors.

Catalysts: The factory cats are excellent quality. DO NOT replace these unless they are absolutely, positively, beyond ANY doubt, failed... either with the honeycomb physically broken/rattling, or plugged up (restricting power). If they are intact and not plugged, but the tailpipe emissions are above spec, can you post the numbers? There are some tips/tricks to getting these to pass a smog test.

 

[Pav2222]

Bi

Thank you very much for your reply!

I was told by an experienced Mercedes mechanic I know in the UK that the ECU needed replacing, that I have a drain on the battery which after removing lots of after market stereo equipment, sat nav etc had reduced the drain on the battery by 90% but there was still a drain.

This is not so much of an issue as I have it on a trickle charger most of the time.

I will let him know what you said about the Cats too.

I would be interested in the ECU you have for sale.

Many thanks

 

[gsxr]

I was told by an experienced Mercedes mechanic I know in the UK that the ECU needed replacing, that I have a drain on the battery which after removing lots of after market stereo equipment, sat nav etc had reduced the drain on the battery by 90% but there was still a drain.

This is not so much of an issue as I have it on a trickle charger most of the time.

A battery drain is a different problem. The ECU is almost certainly not the cause. Most likely it's either a problem with the 38-pin diagnostic port (read this thread for details, especially post 1 and 4), or possibly a defective BM/GM module (the power supply for all other modules). To start with, pull the BM/GM module and see if the power drain stops 100%. If so, it's either the module, or the diagnostic port.