Help. 83 300D 171000 miles.
I'm having external lighting problems and don't know where to begin trouble shooting. Directionals and 4-way flashers work fine as long as the headlights are off. With headlights on, 4-way seems to work ok and the left-turn directional seems OK. Right turn directional flashes as long as the brakes aren't applied, press on brake pedal while right directional is flashing and it stops flashing. Does not happen with left. I changed all rear bulbs, both sides, with correct wattage/type MB bulbs. Cruise, which uses the light bulbs for control is working OK. Headlights/foglights work OK, hi-beam is fine too. I need to start replacing parts but am unsure where to begin. Does the car have a seperate flasher for the directionals and 4-way or is it all in the same unit? Grounds for the rear lights look fine and tight.
Any help most highly appreciated.
Thank You.

Check the ground connections for corrosion around the right side rear light cluster.

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Mick J
'08 Chrysler 300CRD (MB OM 642 engine)
'95 E220 estate
'89 230TE (R.I.P.)

1. I agree with Mick it’s most likely your ground.

2. If not corrosion it might be coming loose or if you have recently had bodywork done it’s paint that needs to be scrapped off at the screw so the ground can be connected fully.

Thai GI sends…

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GI but not GI Joe
They call me "The Thai GI"
Thai in the US Arsenal

OK, On the right side rear is a brown wire, a ground wire, I was told all grounds are brown. It leads up behind the plastic covering in the trunk. I'll have to take all this apart and give it a through checking and cleaning. I did do a cleaning and reattaching of the battery ground cable this summer as part of a general going through my "new" car. Is there some kind of body ground strap someplace that might also need checking?I have other electrical problems, no defroster in rear, radio antenna that worked for a while then stopped, really odd behavior of cruise control, cruise on, press in the left most button on the climate control panel and it disengages the cruise. Pul lever to resume on cruise starts it back up. The car is leaking a bit around the windshield gaskets, frt and rear and I had to fix a giant leak from under the battery so I'm also a little worried thee might be a lot of prblems under the dash. I really kind of hate electrical grief, especially now that it's starting to get wet and cold.
Thanks for your suggestions.

Some work and further explanation of problems. I traced the brown ground wire on the right side to a screw in back of the plastic trunk lining. The wire isn't very well attached and will need to be cleaned and reattached to known good ground. Could a bad ground cause very very odd behavior? For example, headlights on, right directional set to flash, wrong bulb on right flashes, not the amber, but one of the reds, the little side marker bulb also flashes as do, very dimly, the back-up lights. Noticed too, with the light bulb holders removed, the lights on the right are quite a bit dimmer than those on the left and they are all new bulbs. That I know is probably due to bad ground. Does the car have seperate flashers for the 4 way and directionals? How does the plastic panel on the right side come off without breaking it. Thank you for forcing me to do a ground search. If I'm exceptionally lucky this might fix the old thing.

1. Do the cleaned and reattached to known good ground first to see where we go from here…

2. Sometimes the connecter for all of them can be a little corroded, loose or even a hairline crack in the solder and just needs to be resolder, but do number 1 first.

3. Not sure how it looks on your car for the plastic thing, if you already broke it then just move on…


Thai GI sends…

__________________
GI but not GI Joe
They call me "The Thai GI"
Thai in the US Arsenal

Well, I'll certainly be dipped ! Fixed the ground wire, cleaned it up and used a speed nut and a screw to hold it nice and tight. Everything works perfectly! Even the power antenna started working again! I'm just amazed how just having a slightly loose ground could affect so much. Is there any reference material regarding the physical location of various ground attachments throughout the car? Not the wiring diagrams in the Haynes manual or any schematics like that, but a concise list of "brown ground wire attaches to mouning under the seat" things like that? I am now hoping to figure out the rear-window defroster since I now suspect grounding problems and not broken wires since the wiring in the window looks OK. Thank you all for your advise, a happy, crappy MB driver again !

You certainly have my sympathy with all of the little gremlins that appear to be plaguing your car. I've been there with a different car and drove me crazy.
Try something simple first. Replace EVERY fuse in the fuse block with a new one. Don't even think about keeping any of them, just throw them away. While they may look good, sometimes theres a problem that is not readily apparent. It's a cheap way to be certain.
Clean both sides of where the fuse is inserted with a plastic wool pad (3M 'scuff pad' or equivalent) and then place the new fuses where they belong. REMEMBER, make a chart of where the 8 amp ones go, the 16 amp ones go and the 25 amp ones go.
I've done this on a couple of our cars now when something 'funny' begins to happen and it has eliminated a lot of potential headaches.
GOOD LUCK.

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Jay Yambrovich
Scotts Valley, CA.

1993 300 CE Cabriolet (A124) 131K miles
1997 C-280 133K miles

2000 BMW R1100RT 69K miles
1989 300 E 216K miles (sold)

My trunk light (87 300e) glows dim only, even after swapping holder & bulb. Used to work fine. The wires seem to wind though the trunk lid, & I don't know where the ground is to be found.

rmmagow, where did you find the ground for the rear window defroster?
Thanks to all.
Richard

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87 300e (white/black; amg body kit)
88 300ce (red/cream; amg body kit)
93 300ce cabrio (white/blue/blue top)
93 300ce cabrio (black/grey/black top)
98 ml 320 (totaled @ 137,000 miles)
99 clk320 (black/grey/black top)