Chasing electrical gremlin in starter circuit - PeachParts Mercedes-Benz Forum

Alec300SD · #1 09-05-2020, 01:03 AM

Yes, definitely clean all the connections behind the instrument cluster and in the starter circuit (as I had done).
Remember to turn off your radio first and then disconnect the negative battery cable before you start cleaning the connections.
I like to use the DeoxIT-D contact cleaner followed by the DeoxIT-Gold conditioner.

You will want to clean/rejuvenate the battery terminals and clamps, the negative battery cable to chassis connection,
the positive battery cable to starter connection, the starter to alternator harness ring connections, the alternator harness female spade connectors,
the alternator male spade connnectors, the alternator body to chassis ground connection (grounded via the bolts attaching the alternator housing to the alternator bracket),
and both ends of the ground strap between the transmission housing and the chassis (under the exhaust downpipe).

The alternator should have a thin spring steel wire clamp that locks the alternator harness connector to the alternator, if it is missing, the plug can become loose from the engine vibrations.
This can cause inadequate charging and illumination of the instrument cluster warning lamp.

Since the ignition switch is new and there is no NSS, doing the above should hopefully take care of the issues.

blue85' · #2 09-05-2020, 12:34 PM

Quote:

Originally Posted by Alec300SD

Y
and both ends of the ground strap between the transmission housing and the chassis (under the exhaust downpipe).

Thanks for the replies. They are helpful in keeping my mind open to possibilities. This is my first experience in electrical troubleshooting of a "real" nature, and it can get daunting!!

I went looking for the chassi to engine ground, and found one on the drivers side, between the bell housing bolt right at the bottom of the oil filter canister. NONE seen on the passenger side of the vehicle!

Anyhow I cleaned the one I found, and cleaned the grounds behind the cluster. Changed the cluster with another one I Had in stock....

AND I think it has something to do with the multi-pin connection that goes to the instrument cluster. Is that even possible?? By moving that connecter or the wires attached to it, I can get the Glow-plug relay to come on... For the moment I am out of time, and need to drive the car, lets hope it makes the 100 mile trip today, and returns on Sunday. I will be traveling during DAYLIGHT hours only until I get this figured out.