Hello,

On my 85 KaliKar, the right side turn signal stops working if I depress the brake pedal. I notice that the turn signal light stays on solid but dimmed. The brake light does come on but is also dim. I understand that this is probably a ground issue, but I'm not an electrical guy. How do I troubleshoot this?

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Mike Frederick
1986 300SDL, 240K+ miles
1985 300D KaliKar, 270K+ miles

First make sure the bulbs are seated properly in the sockets and the outer shells are not corroded.

You are right this is a ground issue. Check the grounds at the tail light assemblies. These will be brown wires going to the frame in the rear of the car.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Thanks; there is a short brown wire from the right side tail light connector to the body. After much wrestling I got that little 7mm bolt/nut out, sanded the contact surfaces, applied dielectric grease, more wrestling to get the wire/bolt/nut reattached, and it all works.

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Mike Frederick
1986 300SDL, 240K+ miles
1985 300D KaliKar, 270K+ miles

Why you are in the trunk, do the one on the drivers side too....It is right under the antenna motor behind the fender liner.

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So apparently I haven't fixed the problem; in fact, its gotten worse...

Not being an electrical guy, I decided to pull out my trusty multimeter and give a shot at evaluating things within the right-side taillight assembly; specifically the light bar itself.

My multimeter has a audible continuity mode, so I selected that. I figured I should check for continuity between the brown pin on the connector and the metal light bar backing. That should have continuity (all ground), and it does.

But then I tried check the connector from pin-to-pin. I get a tone on every pin combination! That doesn't seem right to me.

Am I doing something wrong, or do I just not understand this at all?

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Mike Frederick
1986 300SDL, 240K+ miles
1985 300D KaliKar, 270K+ miles

I believe you can switch the light bars around, switch it to the other side and see if the problem follows it....then we will know if the issue is inside the bar or with the wiring to the bar.

Another thing, you may want to do is pull the turn signal bulb from the front turn signal and insect it to see if the filaments are good.

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First, I figured-out that the observed behavior was correct; when the bulbs are installed, since there is a common ground, continuity exists between all pins.

Then I pulled the bulbs and there was no continuity between the pins. That made me feel better.

I also went to the car and checked continuity between the ground connector socket and the connection to the fender. Both sides showed continuity.

So here's the current situation--When the brake pedal is pushed: the left brake light and the left backup light come on; on the right all bulbs come on dim.

Help!

Recap: both left and right-side ground connections in the trunk have been removed, the body connection point was sanded, the eye-loop connector was sanded on both sides, and all was reassembled with a coating of dielectric grease.

I have tried three different (existing bulb and new bulbs) in the front right turn signal.

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Mike Frederick
1986 300SDL, 240K+ miles
1985 300D KaliKar, 270K+ miles

Ok well It appears you have some unwanted current path going on. Congrats on the continuity testing and verifying with bulbs out by the way. Here's what I'd be doing pull all bulbs in all corner lenses clean with steel wool the sockets and contacts if you can push the contact out from the wire and also clean that then spray with a contact cleaner. Bench test all bulbs with 12 v and make certain they are also clean. Start putting in the bulbs one at a time beginning with the left rear and test after each bulb goes in. Hopefully it's a bulb or contact issue.

OK, I am still chasing (not very quickly) this problem. The car just failed a safety inspection because when you depress the brake pedal the right turn blinkers don't come on. As soon as you remove your foot from the pedal, they work.

I have removed the light bar and applied a 12V source from the ground to each pin and each light illuminates brightly. I have once again checked the ground wire from the plug to the body of the car. Good continuity. Every light on that corner of the car works fine until you depress the brake pedal.

So I guess now I have to go forward in the car. Is there a possibility of a problem at the brake pedal switch that could cause this problem? I need this fixed and I need to pass inspection. Thanks for any help.

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Mike Frederick
1986 300SDL, 240K+ miles
1985 300D KaliKar, 270K+ miles