Mercedes: mercedes 560 SEL 1986 electrical problem, mercedes shop, diagnostic socket

Question
QUESTION: I own a 1986 SEL gasoline model and the problem is that the motor cranks but doesn't start. The fire doesn't get to the spark plugs the fire stays in the ignition coil. Not sure if it's called the ignition coil I know how it's called in spanish but anyway the fire does not get to the spark plugs. Please help me because where I live there are no Mercedes mechanics and a towing from where i live to the Mercedes is to expensive without mentioning the fees for the repair in the Mercedes shop.

ANSWER: Carmen,
Interesting that you should have this problem, as I too am experiencing the same issues with my 1986 420 SEL.  I will be having a friend look at the engine next week and let you know what I find out.
The vehicle has an overload relay on the fire wall that includes a fuse in the top. Check the fuse. The relay is about 1 inch square and about three inches long. The knife fuse will be under the top cover.

I would also remove the slug fuses one by one and through clean with very fine sand paper the tips. Use 1000 grit paper if you have it. Polish just enough to clean any corrosion and reinsert. You should also carefully remove each relay and clean the connection. Wiggle the relays as you reinsert them as corrosion is a problem with all the electrical components.

Let me know if you have success.

Thanks
Rob

---------- FOLLOW-UP ----------

QUESTION: I'll try that and let you know; but please let me know what you figure out with yours

ANSWER: I have an appointment with a friend mechanic to check it out this Friday, I'll pass along what we find.
Rob

---------- FOLLOW-UP ----------

QUESTION: Have you discovered the problem yet? I am still waiting to see what happens to solve your problem so please let me know.

Answer
Hello Carmen,

My mechanic did a diagnostic on the 420SEL and there is a problem with the ignition switch.
By placing a voltage meter on two of the openings in the diagnostic socket, one can determine if voltage is getting to the system.
Evidently there are some contact in the switch not working.
I have ordered the electrical part of the switch $19.00 on ebay, and when it arrives next week I will install it and we will go from there.

I hope this is the only problem. but we cannot proceed until the switch is replaced.

Please let me know if you have any other questions.
Rob