Funny marker lamp issue

[94heritage]

I am having an issue with the left side front turn signal and marker light on my 86 c30. They stay on even when i turn the key off. Its just the front left the rear does not stay on but it does light up when you flip the turn signal switch on. The lights just stay solid and do not flash either and the turn indicator in the dash stays on as well. I checked both the front two bulbs to see if i had an issue there but i dont see anything strange. Also i have removed both grounds on the rad support and cleaned those up. I pulled the flasher canister out of the fuse box and they still stay lit up. Any other thoughts as to why they stay on even when the key is off?

 

[Georgeb]

Has there been any aftermarket wiring added or other work performed on the truck? Your problem is most likely something back feeding or getting it's ground through that circuit. Here is a diagram of part of that circuit. The lines leaving the bottom of the image are all grounds and I would guess there is an issue with the brown marker light circuit.

 

[chengny]

Try pulling the flasher relay for the hazard lights and see what happens.

You note that the condition exists even with the key turned off. Power to the hazards is always available - regardless of ignition switch position. On the other hand, power for the directionals is ignition switched and should be unavailable unless in RUN or ACC.

 

[94heritage]

Well I have tired taking both the flasher and hazard relay completely out and the front marker stays on still. If you turn the head lights on the side marker on the fender goes out. But the one on the passenger side fender is on. This thing is killing me. Ive tried checking all my grounds and making sure they are clean. Do the lights ground through the housing as well?

 

[75gmck25]

Is your instrument panel ground wire connected to the cluster? On my truck the black ground wire is connected to a post on the emergency brake mechanism, but on newer trucks I think they added a separate ground point up under the dash.

The other grounds you need are the grounds at each tail-light and marker light, and the two grounds under the hood that connect to the radiator support (the right side radiator support ground also grounds the battery to the radiator support). There is also a large white ground wire under the back bumper, connected to the frame.

Bruce

 

[94heritage]

I dont see a white wire near the back bumper let alone a white where anywhere near the rear of the bed. Im going to check the dash grounds and see if there is wire to the parking brake pedal.

 

[Rusty Nail]

The problem is definitely the 1157 bulb in ge back.

 

[94heritage]

Im not having any issues with the tail lights though. They work as they should. Ill pull the bulbs and check them

 

[Georgeb]

Try pulling one fuse at a time until the light goes out. That may help you narrow in on the problem. Pay attention to which fuse it is.

 

[da_raabi]

Try pulling one fuse at a time until the light goes out. That may help you narrow in on the problem. Pay attention to which fuse it is.

This should work.

Did you ever figure it out?