What is the procedure for replacing the engine control module on 92 500SL? The Mercedes mechanic(?) says he is 95% certain my problem is a faulty ECU. Problem is he wants me to purchase a new part from MB dealer for around $2700 and would not consider a used part even though based on a guess. I decided to try a used warrantied part and gamble on a $500 part vs his $2700 part and install it myself. Now I need help with details of installing the ECU. It is my understanding, after installing the ECU, the battery must be disconnected for 1.5 to 2 minutes then reconnected after turning ignition to on position. Does anyone know proper method of installing the ECU? Appreciate any info.

what is the part number? i will see if it needs version coding

The ECU part number is 012 545 5732.

ON that & all models thru 1992 the engine computer is PLUG & PLAY!


Starting in 1993 with the 300E the HFM-SFI computers require version coding.
Then in 1996 all fuel computers require version coding..

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

Thanks much M.B.Doc.
You have impressive resume. When I was looking for a replacement for original part #010 545 9532, I was told by 3 dealers that current part available is #012 545 5732 with part #012 545 2232 between original and present. Assuming the dealers are correct, is there a difference in these parts that require anything other than "plug and play" as you described for installation. I was able to purchase a used "012 545 5732. Also, is there a special sequence to disconnecting/connecting battery and turning on ignition...understanding that memory will be lost when battery is disconnected. Sorry if I sound stupid but, I am when it comes to understanding modern auto electronics.

Simply plug & play! IF the ECU is truly the problem!

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

You can 'bridge' the new part in over the old; just disconnect the leads from the DI Module; mount the new one 'temporarily' over the old part and connect the leads as shown in the outline picture in Menu #5. You'll see connectors "A" and "B" along with 1, 2, 3 and 4. You do not have to disconnect the battery.

If the DI Module is bad, and the new one "good" it should fix the problem.

As far a 'codes', they are analog and can be read . . .

__________________
Regards . . . . JimF
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'94 S500 Cpe

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