Unique turn signal/brake light issue

[75gmck25]

I have some additional grounds you should check, clean up the metal to metal area, and retighten.

- On the radiator core support for headlights- one black ground wire on each side. The passenger side ground point should also have a wire running over to the battery negative.
- Ground from engine to body - usually near the back of the passenger side valve cover area. A braided ground wire running from the engine over to the body right behind the valve cover.
- Ground from engine to frame - braided ground wire, usually near the fuel pump on the passenger side, running from the engine to a bolt into the top of the frame.
- Ground from tail-light wiring to frame - White wire coming out of the rear wiring, right behind the license plate
- Very important - instrument panel ground. Black wire from instrument panel that is either connected to a post on the emergency brake mechanism, or on later trucks to a grounding block up under the dash.
If this wire is not connected, the gauges and lights will find a ground through other paths, which causes all kinds of weird gauge and panel indicator behavior.

Bruce

 

[Dusty Trails]

@gpmorgan - without you long haul drivers we wouldn't have the goods we need so thank you. Update on the brake light for you and @Honky Kong jr - The added ground helped as it exposed the real issue. Adding the ground gave me a low beam tail light when I applied the brakes and flipped the left turn signal switch on the driver's side with the truck running (somehow). It turns out someone added a splice to the hot wire into that taillight socket and had covered it with tape. There was corrosion down the wire as far as I could see. I cut the bad copper and soldered it back together and for now it works! I'll probably have to replace the wire before too long, it looked pretty bad. Just wanted you both to know your suggestions were really helpful. I knew I could rely on other guys with bowties.

 

[Honky Kong jr]

@gpmorgan - without you long haul drivers we wouldn't have the goods we need so thank you. Update on the brake light for you and @Honky Kong jr - The added ground helped as it exposed the real issue. Adding the ground gave me a low beam tail light when I applied the brakes and flipped the left turn signal switch on the driver's side with the truck running (somehow). It turns out someone added a splice to the hot wire into that taillight socket and had covered it with tape. There was corrosion down the wire as far as I could see. I cut the bad copper and soldered it back together and for now it works! I'll probably have to replace the wire before too long, it looked pretty bad. Just wanted you both to know your suggestions were really helpful. I knew I could rely on other guys with bowties.

Cool

 

[Dusty Trails]

@75gmck25 - Through this taillight journey I was able to find all of the grounds you mentioned and have cleaned up all those connections save for the white wire behind the license plate. No extra ground there. Everything else is shiny and snugged tight. I appreciate you very much for the details. Your truck looks great. I hope mine grows up to be that handsome some day.