92 C124 M104 No Spark at ICM/EZL - PeachParts Mercedes-Benz Forum

ronald7410 · #1 02-11-2015, 01:22 AM

My car overheated the other day and I ended up having to tow it to a local shop who had fixed that problem by changing out the thermostat, reservoir sensor and fluid.

Upon leaving the shop, the car didn't want to turn over. He tries cranking it for about 10 seconds at a time with no turn. He checked the engine code and started analyzing the components that led him to the Ignition Control Module (ICM). He tried placing a spark plug on the ICM with no spark then concluded to replace the Crank Sensor. This didn't work. He concluded the ICM is faulty. I'd bought a used one and this still didnt work. As of now my car is immobile until I find/suggest a solution to him.

What supplies power to the ICM? How can I root this problem?

rayhennig · #2 02-11-2015, 10:43 AM

Quote:

Originally Posted by ronald7410

He tried placing a spark plug on the ICM with no spark

I don't understand that. He must place a spark plug on the coil in order to see a spark. Please can you make this clearer.

All the best.

RayH

Elektri · #3 02-11-2015, 11:27 AM

There is a whole set of Factory Service Manual tests to check the various components with a multimeter and/or scope.

This was not done? (A bit of time testing can save a lot of money part buying!)

ronald7410 · #4 02-11-2015, 11:37 AM

Quote:

Originally Posted by rayhennig

I don't understand that. He must place a spark plug on the coil in order to see a spark. Please can you make this clearer.

All the best.

RayH

Yes he did place it in the coil and had no spark.

Quote:

Originally Posted by Elektri

There is a whole set of Factory Service Manual tests to check the various components with a multimeter and/or scope.

This was not done? (A bit of time testing can save a lot of money part buying!)

Yeah he read code 11 which went through 4 steps which led him to the last one of replacing the unit.

Keep them coming, this forum is way more useful than mbworld/benzworld. Thanks guys!

Elektri · #5 02-11-2015, 11:57 AM

Did he actually take out a multimeter and take voltage/ohm readings on the coil before replacing it?

ronald7410 · #6 02-11-2015, 04:10 PM

Quote:

Originally Posted by Elektri

Did he actually take out a multimeter and take voltage/ohm readings on the coil before replacing it?

The coil where the spark plug was placed? This was never replaced. Just the ICM and the crank sensor. Neither was the problem.

Frank Reiner · #7 02-11-2015, 05:18 PM

1992 Model Year? With a distributor and a single ignition coil, or, no distributor and three double coils?

ronald7410 · #8 02-11-2015, 06:34 PM

Quote:

Originally Posted by Frank Reiner

1992 Model Year? With a distributor and a single ignition coil, or, no distributor and three double coils?

Not sure which one it is. But it's the early 104 with the pan type air filter. Does this answer your question?

rayhennig · #9 02-12-2015, 12:47 AM

Quote:

Originally Posted by ronald7410

Not sure which one it is. But it's the early 104 with the pan type air filter. Does this answer your question?

Yes it's engine M104.980 with KE Jetronic injection.

RayH

ronald7410 · #10 02-12-2015, 10:17 AM

Quote:

Originally Posted by rayhennig

Yes it's engine M104.980 with KE Jetronic injection.

RayH

I have CIS injection.

rayhennig · #11 02-12-2015, 12:42 PM

Quote:

Originally Posted by ronald7410

I have CIS injection.

Yes, Constant/Continuous Injection System: the Bosch KE Jetronic, just like mine!

All the M104.980/981 engines had it. Great engine to my mind with 7K rpm and real straight 6 smoothness. I used to have V8s but I enjoy this more, especially as I live deep in the country and the 5-speed auto can make the engine single beautifully.

Mark you, I wouldn't mind a 500E though!

R

ronald7410 · #12 02-12-2015, 01:54 PM

Can anybody conclude a part that could be causing my engine to not spark? I've ruled out the parts discussed above.

Frank Reiner · #13 02-12-2015, 03:32 PM

ronald:

Please understand that these comments are not intended to show you any disrespect at all, simply to state what seems obvious.

The answer you gave to the question about the configuration of the ignition system indicated that you are not practiced in automobile mechanics; you were not able to identify the system.

The person who has worked on the car up to this point seems limited to reading codes, but does not have a good understanding of the most basic physics involved in the generation of ignition sparks. That person also may not understand that tracing through all of the power supply wiring that is a part of the primary side of the ignition system is a necessary first step. If power is not reaching the EZL (the ignition control unit), an infinite number of parts can be changed, to no avail.

Attempting to pass information through a third party, who may, or may not be a native English speaker, introduces an additional degree of error.

Folks on this forum will strive to help, but a clear dialog is going to be necessary.

ronald7410 · #14 02-12-2015, 05:36 PM

Quote:

Originally Posted by Frank Reiner

ronald:

Please understand that these comments are not intended to show you any disrespect at all, simply to state what seems obvious.

The answer you gave to the question about the configuration of the ignition system indicated that you are not practiced in automobile mechanics; you were not able to identify the system.

The person who has worked on the car up to this point seems limited to reading codes, but does not have a good understanding of the most basic physics involved in the generation of ignition sparks. That person also may not understand that tracing through all of the power supply wiring that is a part of the primary side of the ignition system is a necessary first step. If power is not reaching the EZL (the ignition control unit), an infinite number of parts can be changed, to no avail.

Attempting to pass information through a third party, who may, or may not be a native English speaker, introduces an additional degree of error.

Folks on this forum will strive to help, but a clear dialog is going to be necessary.

I understand I'm practically playing telephone and to be honest I would not have picked this shop as my first option for my car but my car stopped on me unexpectedly and I did not want to pay for a tow truck to drive my car 45 miles away.

I'm not expecting you or anyone to know the exact answer to the problem but I'm trying to get a consensus of the common problems that could cause this to occur. If I could at least keep this discussion open it would help me from paying hefty fee to tow my car.

I appreciate your comments and and still persistant on finding a solution to my dilemma.
Thanks for your help

Frank,
I notice you're in Modesto. My car is in a shop in SF and would rather have knowledgeable mechanic work on it. If you know anybody in the city that can troubleshoot this I'd be happy to tow it there. Let me know.
Thanks.

Ferdman · #15 02-13-2015, 07:54 AM

ronald7410, how do you know that the used ICM is good? Best to exchange the ICM from an engine that runs into your vehicle temporarily to check if your engine will start, or better yet, exchange your ICM into a vehicle that runs to confirm that your ICM is bad. Otherwise, you have no idea whether your ICM is truly bad. That particular ICM is sensitive to weak ignition components so you need to perform routine maintenance/replacement on the ignition system (spark plugs, ignition wires, distributor cap & rotor). Once you confirm that the ICM is good you can proceed from there to diagnose the no-start problem.