m3rcedes

Hello comrades,
I got in crazy situation. Car W221 S500 4 Matic 285kw, current ECU had problems with simultaneously working engine (auxiliary) fan, while I was looking for solutions, one day my ECU died, had to tow my car, everything was blocked, abs module, gearbox, lights module, lots of error.
So now, I tried to to smth probably stupid. I bought a used ECU from different Mercedes model. Long story short, We copied all the information to new ECU, the car recognizes ECU from OBD, but I got lots of CAN BUS error messages. The question - Is it possible to do such think, swap ME9.7 ECU from different model or I'm stuck and need identical ECU that's already in my car? Can I use a different ME9.7 ECU on my w221 ?

My car and ECU
W221 2007 S500 4matic 285kw - Engine Code 273.968 Bosch nr. 0261209210 👇

A "new" ECU that I bought is from ML W164 2009 5.5L 4matic 285kw Engine Code 273.963 Bosch nr. 0261209380 👇

FAULT ERRORS with "new" ECU

BOTUS

you can with the right tools use secondhand parts - not tried but of course this will be one of the hardest modules to fit and get to behave - as it the one you need to steal a car

all the other bugs and issues are not related to the engine ECU the car have up to 60 module that can all lie and complain about anything

the issue you likely have is low voltage and a load of lies - what age - if 2006 / 2007 it may well have two batteries and BOTH need to be tip top and with voltage support to do any sensible diagnostics
and if that's not getting any sense - likely a puddle in the electrics or or blew some pre-fuse boards

BOTUS

if the ecu is the same component - but programmed for a totality different vehicle model - I expect you'll have serious issues - they try to stop people stealing and reprogramming - forcing in the chassis number and linking the immobiliser bit ( I can image working) but those to actions need the tools the dealers pretend don't exist and the expertise re the tricks on making it a success

I think you need to virginise the unit to a blank one and programme as if its fitting a new part using dealer tools

m3rcedes

I have 2007 model which has two batteries, under the hood it's 52Ah and in the trunk 90Ah, last time I've checked, the trunk had 11.50v, by the charts I believe it's ~30% charged. The battery will be charged, then I'll try again.
As for programming, the guy who did it used K-TAG software. Right now I have no connection to gearbox, to abs modules, ignition works, OBD connects only to ECU and other non major blocks.
@BOTUS so, you're saying that IT IS possible to connect a ECU from different model, but it needs to be programmed correctly?

BOTUS

both batteries need to be 100% then you turn the key on and for prolonged diagnosis they are usually dead enough inside 25 mins they start throwing more errors than you had before you stated looking - I don't bother to try and scan anything unless I add battery support

with the ignition on they eat 37 amps with the engine off

BOTUS

if the rear is under 11.9v it will create fake errors in diagnostics - need to stay above 12.1 to not throw faults and 12.5 is a better idea

re ECU I guess its possible but this is not an area I have studied

m3rcedes

Update for the future fellas
If you have W221 S500/S550 with M273, the only ECU's compatible are the one's from CL W216 M273 or W221 M273 ( because their CAN bus works on the same frequencies ), check your car's VIN nr.
YOU CAN'T SWAP ECU FROM DIFFERENT MB MODELS like I tried to do by using ML500 W164 ECU. The problem is that the second CAN BUS line on the other MB ECU models are working on different frequencies, that's why my W221 gearbox, abs, lights etc. modules didn't received signal from ECU. The ECU from W164 itself works perfectly fine, but it's not compatible.

For me, I had the old one with A2731535079 and now I bought a latest with A2731535679
We moved the key information from old to new, plug 'n" play, and problems got away.

Hope it will help someone. ❤

saturnoAR

How did you find that compatibility?