Ignition Control Module Question
 

My question may pertain to all MBs but I am asking specifically about a 1989 560 SL. The question is will the ignition control module fail all at once and completely or are there preludes to failure. My MB will crank forever in order to start but once started runs perfectly. I have replaced almost everything on this car except the drivers seat which needs replacing. This includes every fuel related part except the fuel distributor.

I think it might be the drivers seat....(bg)....

I doubt it is the ignition module they usually are in or out and the don't change. I have seen exceptions.

I would suspect the OVP and or ignition rotor/coil.

On the ignition side I have already replaced the rotor, cap, wires and plugs only thing left is coil and have a new one coming. I was pretty sure by process of elimination that it would be the coil, but was unsure of EZL. I will not at this point, however, rule out the drivers seat. I have read every thread on this site about every aspect of hard starts. This it seems is the most elusive diagnostic challege for MBs.

Ignition coils have bitten a lot of Mercedes technicians........ more than electrically! The test procedure written by the factory for the coil is by far one of the most inconclusive ways to check a coil.

Need to do a Max kV output test to truly determine a coils capability, a resistance test tells you the windings are ok!

:cool:

The new coil came in and I installed it 2 days ago. This was in fact the problem. I guess I've never seen a coil get progressively weaker over time. My experience was that they may cause problems while the engine is running and finally failing abruptly. This one caused progressively harder and harder starts but once started the engine ran fine. Hope this information helps someone in the future. FY the car has 124,000 miles on it. Many great posts have helped me do a lot of good maintenance on this car which now runs like the dream in which it was created.