No ECU after flat battery

[EmilysDad]

Well done on the repair!

How did you know which chip you were swapping?

 

[ajlsl600]

OK - Problem has now been solved - I bought a 2nd hand ECU with matching part number, software version and Q number (not sure if the last 2 specifics are important or not) - The ECU does not need to come from the exact same model of car I believe - just match the numbers.
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I opened up both old and new ECU's and located the chip which needs removal - (shown circled) and marked the old board with sharpie - I also added a very small dot of nail varnish to the top edge of the chip I wanted to remove with a pin - This helps to keep track of which is old chip and which is new chip (in case of sudden gust of wind or something - it also helps when fixing the chip onto the new circuit board to ensure it is the right way up!)

View attachment 54055
You need to remove the circuit boards from the metal housing - Some mild heat may be necessary to soften the sealant holding the back plate onto the circuit board.

Next - I cut out some kitchen foil peices with a chip sized hole in them to act as a heat shield - I used 3 layers.

Then, I heated both boards in the oven to 100 degrees c just to help prevent shocking the boards when I used the heat gun - I put both in with the oven cold, and let it get to temperature - then removed.

On a flat surface I then added the heat shields and used a hot air gun set at 365 degrees and wafted this over the chip pins on the "new" ECU VIN chip, going round the chip for about 10 seconds while holding the chip with tweezers - once free of the board, discard this chip.




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Returning to the cars original board, I removed the same chip and kept it safe.

On the "new" circuit board, I cleaned the 8 tracks where the chip pins go with a quick run over each one with a soldering iron, then carefully placed the chip I had been keeping safe onto the board, and held in position with tweezers while I fixed each chip pin to the board with a soldering iron.
View attachment 54060

Allow to cool, reassemble into the metal housing, and refit (with the car battery disconnected) - and as if by magic I have a car which starts again for the princely sum of £33 in parts - and not some horrendous invoice from a specialist!

you did very well! lets hope they dont start building boats !!

 

[lordgaz]

Is your SAM in the same enclosure, as mine is?
I've seen SAM's go down due to ingress, well doing strange things with lights and horn. But on oldish MB's they're just plug and play when a same SAM is sourced.

Funny you should say that - Since doing this job, I have noticed one (only O/S) reversing lamp has decided to come on when the car is switched off - but does the front right (O/S) SAM have any control over the rear lights? I've just taken the front right SAM out and it appears to be perfect inside - no corrosion on the metal tracks, or indication of water ingress inside the circuit board..

Does any one have any solid information about which SAM has control over the reversing lights?

 

[lordgaz]

Well done on the repair!

How did you know which chip you were swapping?

I saw it on a video on Youtube - but I only took a screen shot of the video and didn't save the link.. if I find it I will post.

 

[M80]

In the Vito / Viano there is only the front SAM. I'm aware of some having a rear SAM.
So in my case Yes the front SAM controls rear lights.

Perhaps a little late for you but I carry a spare SAM (the original that went u/s) that has a known fault. If this one plays (assuming with a different fault) up I can swap out and prove / disprove.

 

[lordgaz]

In the Vito / Viano there is only the front SAM. I'm aware of some having a rear SAM.
So in my case Yes the front SAM controls rear lights.

Perhaps a little late for you but I carry a spare SAM (the original that went u/s) that has a known fault. If this one plays (assuming with a different fault) up I can swap out and prove / disprove.

I have a spare somewhere.. I’ll try and swap it over and see if anything improves


Sent from my iPhone using Tapatalk

 

[EmilysDad]

I saw it on a video on Youtube - but I only took a screen shot of the video and didn't save the link.. if I find it I will post.

I was impressed that you knew which bit .... the de-soldering re-soldering bit was the easy bit if you knew which bit to replace.

 

[daibevan]

Just read this thread. WOW well done that man.

 

[lordgaz]

Funny you should say that - Since doing this job, I have noticed one (only O/S) reversing lamp has decided to come on when the car is switched off - but does the front right (O/S) SAM have any control over the rear lights? I've just taken the front right SAM out and it appears to be perfect inside - no corrosion on the metal tracks, or indication of water ingress inside the circuit board..

Does any one have any solid information about which SAM has control over the reversing lights?

Just to wrap this thread up, I bought a 2nd hand SAM module with matching part numbers and pulled out the old one (Drivers side under the bonnet) - I had suspicions it had become wet, but could not find evidence - anyway, spurious reversing light issue has gone (maybe a coincidence) - and the car drives great.

 

[grahamcol]

Well l'm vastly impressed with the op's knowledge and skills here. Makes me very proud to be a member of this excellent forum. Well done on keeping an old Merc on the road at minimal cost.

 

[lordgaz]

Well l'm vastly impressed with the op's knowledge and skills here. Makes me very proud to be a member of this excellent forum. Well done on keeping an old Merc on the road at minimal cost.

I agree, this is a great forum - plenty of experiences and knowledge shared. Although I hate it when a vehicle gets a problem, I always feel reassured that this forum can help in some way, and if it cannot, I do like the challenge of having a go and posting the results if it can be in any way helpful to others. Owning an (old) Merc does not need to be a massive drain on the wallet.. And thank you for the compliment, but I figure I am perhaps only an average "at home" mechanic, same as many others here - but because Mercs are so well thought out it only requires being careful and methodical to do most jobs. One can do most things with some planning and research of info on here.

 

[AMGeed]

Well done on that repair! I wouldn't have the confidence myself, so hats off to you.

 

[grahamcol]

Well op whether you consider yourself "average" or otherwise you certainly nailed that particular problem. I guess each of us has a specific area where we are better or poorer than average. Yet to discover mine though ! I've been on this forum and on the other side ( much less) for over 10 years now and thanks to the very knowledgeable members l've gained much general knowledge, resulting in several successful fixes to my own cars. Doubt l'd have been able to sort this particular ECU problem though !