Help with a couple electrical issues '90 300E - PeachParts Mercedes-Benz Forum

Andy_M · #1 09-10-2010, 06:54 AM

I could use some help with 2 issues. Anyone who has experienced either of these please let me know what solved your problem.......

1) I think this may be a relay issue.....ALL windows intermittantly, and seemingly randomly, refuse to work. When this happens NONE of the window switches nor the sun roof will work....not even the switches on the doors. If they are down they won't go up and visa-versa. Turning the key off one or more times "fixes" it. This is happening more and more frequently.

2) This one is really wierd. Sometimes when the right turn signal is on, and the headlights are on also, if I step on the brake the turn signal stops blinking. Take my foot off the brake it starts again. Turn the headlights off and it works fine. I don't know that I can draw a solid conclusion, but it seems like it happens more after a rainstorm or heavy dew. However I can't find anyplace that seems to be getting wet in that circut.

punkinfair · #2 09-10-2010, 07:22 AM

#2 sounds like a bad ground somewhere in the lights. on an older car the fix for this is to remove all the bulbs, clean sockets and bulbs, reassemble with some dielectric grease. the light housings have multipin sockets on them, remove the plugs, clean inside, grease. find the brown ground connections for the lights, remove and clean, reassemble. if you do this on all the exterior lighting the issue will surely disappear.

mak · #3 09-10-2010, 09:33 AM

clean out the ground connections and pins, the ground wire is always BROWN in colour.
Also surprising as it may be ,replacing all the fuses with fresh ones will save you a lot intermittent electrical problems.this is due to erosion of the old fuse ends and oxidation of contact areas.
mak

Andy_M · #4 09-13-2010, 12:35 PM

Quote:

Originally Posted by punkinfair

#2 sounds like a bad ground somewhere in the lights. on an older car the fix for this is to remove all the bulbs, clean sockets and bulbs, reassemble with some dielectric grease. the light housings have multipin sockets on them, remove the plugs, clean inside, grease. find the brown ground connections for the lights, remove and clean, reassemble. if you do this on all the exterior lighting the issue will surely disappear.

Wanna bet ?

Should have said so, I appologize, but did all that already...except the grease. Didn't have any at the moment. but disassembled, wire brushed, contact cleaned, and reassembled. Still does it.

Andy_M · #5 09-13-2010, 12:36 PM

Quote:

Originally Posted by mak

clean out the ground connections and pins, the ground wire is always BROWN in colour.
Also surprising as it may be ,replacing all the fuses with fresh ones will save you a lot intermittent electrical problems.this is due to erosion of the old fuse ends and oxidation of contact areas.
mak

interesting thought. I'll try this.