Need Help Re Engine Control Module - PeachParts Mercedes-Benz Forum

Don Moranville · #1 04-06-2006, 02:03 AM

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.

#2 04-06-2006, 02:16 AM

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

Don Moranville · #3 04-06-2006, 02:29 AM

The ECU part number is 012 545 5732.

mbdoc · #4 04-06-2006, 08:11 AM

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..

Don Moranville · #5 04-06-2006, 12:54 PM

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.

mbdoc · #6 04-06-2006, 03:47 PM

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

Don Moranville · #7 04-10-2006, 02:30 AM

M.B.DOC You sound skeptical regarding the problem and reason for replacing ECU. The problem began about 2 months ago when I started engine. It would barely idle with Bat., ASR, and ABS lights on, then would pick up speed, lights off, and seemed to run alright except for occassional miss. This behavior happened a couple more times then while turning a corner at 20m.p.h. the engine went into same mode like limping in slow rough idle and barely made it home. Now it very difficult to start, barely runs in slow idle with Bat., ASR, and ABS lights on and never comes out of this condition as it did earlier. Any suggestions what may be wrong other than defective ECU?

JimF · #8 04-10-2006, 11:12 AM

After buying a '94 S500 Cpe and running it for about 2 years, the CEL came on. Car ran fine but after reading codes (DTCs), it 'pointed' to the DI Module (Menu#5).

At that time a new ECU was $1700, so decided to 'learn' about MBs and fix it myself. That was the start of what is now my "My S500 Cpe" web pages.

The DTCs from the DI Module; PN 015 545 61 32:
Active--------- CKP Sensor Defective (L5)
Registered------ N/F
Stored--------- N/F
N/F = No Faults

It appeared as an "active" fault and that turned the CEL on. Since it was an active fault, it wouldn't erase. It appears that the Diag memory in the DI Module that stores 'faults' went bad similar to a bad memory element in your computer's SD-RAM. It fault pointed to a "CKP-sensor" which wasn't really bad!
Unfortunately, the only way to fix it was to replace it.

Found a replacement for $225 in a NYC junk yard and that fixed the problem and still going strong today.

Check out my various sections for other info.

mbdoc · #9 04-10-2006, 12:33 PM

No problem with different folks putting their 2 cents into the pot....HOWEVER the 1992 500SL doesn't have electronic fuel injection & therefore no diagnostics of any engine control system other than the fuel system.

People can get confused by mis-information.

ON that CIS-E system trying anouther computer is a logical diagnostic step!

JimF · #10 04-10-2006, 08:24 PM

Quote:

Originally Posted by Don Moranville

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.

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 . . .

Don Moranville · #11 04-10-2006, 11:39 PM

JimF...I visited your website and wondered if there is any notable differences between the 94 S500 and 92 500SL
It appears that Engine Control Module and Ignition Control Module (N1/3) are being used interchangeably, is this so? Or is the ignition control module an integral part of the engine control module. I noticed when I pulled the plugs on left side (drivers side) they were all wet indicating no spark also it appears that 2 ignition wires from left coil go to right side and vice versa 2 from the right side go to left bank. Plugs on right banK (passenger side) were dry indicating that they were firing. This would indicate both coils are OK since plug wires to each bank come from both coils, or am I wrong. Appreciate the help I have been getting from the forum.

JimF · #12 04-10-2006, 11:51 PM

The key question is; does your present DI Module (some call it "Ignition Control Module") look the same as the picture in Menu #5?? The ICM is located on the driver's side fender well.

I think you will find they 'look' the same but there's certainly a large difference since the part numbers are so different. Are they interchangeable?? Don't think so.

Test the one you bought by using the setup I described in post #10.

deanyel · #13 04-11-2006, 11:48 AM

A 1992 500SL should be a KE engine management system, a 119.960. Jim's 94 coupe is an LH engine management system, a 119.970, that came out in the coupe at the start of production in 1993. The LH system followed the KE system in the 500SL, I believe at the start of the 1993 model year, and ran through 1995. In any case your engine number will tell you which you have. In other words even the system that came after yours didn't require programming. If you've got the replacement part, why not just give it a try?

brothers123 · #14 04-11-2006, 12:14 PM

Dan,did your mechanic try the over-load protection relay? Are all the fuses ok? Start with the simple tihngs first. HTH Later Emir

mbdoc · #15 04-11-2006, 12:47 PM

AS I posted the later LH-SFI fuel systems have NOTHING in common with the CIS-E cars & that even though the ignition modules LOOK the same they WON'T interchange & they have no diagnostic ability.

That is how mis-information causes problems! You guys work it out!