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Discussion Starter #1
I'm trouble shooting this condition. The fuel pump relay was recently replaced. Vehicle ran fine a couple of days ago. Discovered a very dead battery which I've charged. Now it cranks but won't start. Where is the ICM? One other note: I removed the cruise amplifier and sent it off for repairs. Drove the car without it so I don't think that is the issue. What do I need to check?
 

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1986 560 SL
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Fuel, spark.
Spray some starting fluid in the air intake. If the engine then starts, you have a fuel problem. If it doesn’t, you have an ignition problem.
 

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Discussion Starter #3
Thanks, dugald. I'll start there. It has a new distributor cap and wires. I'll get some starting fluid and see what happens. Should I spray with the air cleaner on or off?
 

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1983 380 SL
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If you mean to the coil, it is intact and firmly connected. Not sure where it goes from there. How would I test the coil?
The green wire goes from the distributor to the ICM on the fender just forward of the ignition coil. I had an intermittent no spark problem that I tracked down to the infamous green wire. I ordered a new one from a less than reputable supplier that came with it's own built in intermittent problem. They did however stick to their word an sent me a replacement green wire once they corrected their manufacturing error.

Here is a picture showing the Green wire. It's the thick wire running from the distributor to the ICM (square box to the right of the distributor in the picture). Even if it appears to be making a slid connection, it still could be bad. Won't hurt to check it. In fact, if it's 30+ years old replace it.

The picture is of a mock-up of the ignition system I assembled on the bench to track down my no spark problem. After I found the problem, I could generate a spark by spinning the distributor gear and I could see the spark jump on the spark plug sitting on the top of the battery over on the right (the spark electrodes are just out of sight).

IMG_0919.JPG .
 

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1983 380 SL
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Found the ICM with the green wire running to it. How to test the ICM?
Best way to test the ICM is to replace it with a modern (solid state) replacement. They're not very expensive.
 

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Discussion Starter #12
Thank you Jyuma. I found the ICM on the left front fender well. While I hate to "easter egg" a problem as you note this is an '83 so I might as well give a new ICM a shot. I don't see where the green wire terminates into the distributor, though. I'll keep hunting.
 

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1983 380 SL
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Thank you Jyuma. I found the ICM on the left front fender well. While I hate to "easter egg" a problem as you note this is an '83 so I might as well give a new ICM a shot. I don't see where the green wire terminates into the distributor, though. I'll keep hunting.
It enters through the side... I'll look for a picture.
 

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1983 380 SL
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There is a metal strip (cover) that holds the green wire in the connector on the side of the distributor. If I remember correctly it's on the left side of the distributor as you face the engine.
Note: these pictures are all upside down.

IMG_0921.JPG IMG_0925.JPG IMG_0923.JPG
 

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1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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The green wire goes from the distributor to the ICM on the fender just forward of the ignition coil. I had an intermittent no spark problem that I tracked down to the infamous green wire. I ordered a new one from a less than reputable supplier that came with it's own built in intermittent problem. They did however stick to their word an sent me a replacement green wire once they corrected their manufacturing error.

Here is a picture showing the Green wire. It's the thick wire running from the distributor to the ICM (square box to the right of the distributor in the picture). Even if it appears to be making a slid connection, it still could be bad. Won't hurt to check it. In fact, if it's 30+ years old replace it.

The picture is of a mock-up of the ignition system I assembled on the bench to track down my no spark problem. After I found the problem, I could generate a spark by spinning the distributor gear and I could see the spark jump on the spark plug sitting on the top of the battery over on the right (the spark electrodes are just out of sight).

View attachment 2639013 .
So URO corrected the problem with their replacement or was it another supplier? Don't remember anyone posting that. Good to know.
 

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1983 380 SL
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So URO corrected the problem with their replacement or was it another supplier? Don't remember anyone posting that. Good to know.
Yes, it was URO (I didn't want to pile on) and yes, months later, long after I had for gotten all about it, a package came in the mail with a replacement Green wire. The original was still working with the modification they (URO) had suggested, so I just put the replacement Green wire in stock. Seems my stock of Mercedes parts keeps growing.
 

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1983 380 SL
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3,013 Posts
Thanks again, Jyuma. Where did you get the replacement?
You can get it from AutoHausAZ but be warned it will be URO. Many people on this forum don't much like URO. I have used many URO parts and have been satisfied with their quality, but I might think twice about using a URO part in hard to reach places.

The Green wire is easily replaced and you could buy two URO Green wires for the price of one from other suppliers.

 

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Discussion Starter #19
You can get it from AutoHausAZ but be warned it will be URO. Many people on this forum don't much like URO. I have used many URO parts and have been satisfied with their quality, but I might think twice about using a URO part in hard to reach places.

The Green wire is easily replaced and you could buy two URO Green wires for the price of one from other suppliers.

Thanks, that answers the question as to whether they corrected the fitment issue.
 

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Discussion Starter #20
ICM has arrived, a HUCO. It came with a very small tube of a white material that I am assuming is a dielectric grease for the contacts but before I start slathering an unknown material on this new part I thought I would ask to be certain.
 
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