Electrical gremlin

[germando]

So got a little bit of an issue let’s get right to it. So with headlights off all signals work properly. However if you turn on the headlights, the reverse lights also come on and the rear turn signals do not work. The side indicators still work just not the main break lights. Before I get all down and dirty with it just wanted some opinions. Gut feeling is a ground as I don’t believe the back up lights and headlights share any circuits except a common ground.

Thoughts?

G

 

[Jgonick]

Usually bad or wrong bulb or ground.

 

[Ricko1966]

I don't think your headlights have anything to do with it. Unplug them see if you still have the problem.

 

[PrairieDrifter]

I recently had a bad rear passenger sidemarker bulb make the drivers side brake light stay on only when the marker lights or all lights were on. Then the front signals worked properly but the rear drivers side stayed solid on.

All of that and that sidemarker bulb still worked proper but it looked like it burnt up so I wasn't convinced since it still worked. The main tell was that the brake light was only on with the lights on, so not a constant issue with wiring just a bad bulb. I was for sure scratching my head for awhile there, since the all the lights "worked"

Long story short, electrical isn't as straightforward as we're are led to believe.

 

[RustyPile]

The light issues you're having are typical symptoms of loss of or missing grounds. There is no set of detailed instructions for repairing a specific symptom of a bad ground. Grounding is a system, not a single circuit application. Pointing to a specific faulty ground is at best, difficult.. Voltage in every circuit on the truck HAS to have a path back to the battery. The frame, and various body parts provide that path.. Ground straps and ground wires also provide that path.. If there is an interruption in this ground path anywhere, the voltage will "wander all over the place" looking for a path back to the battery. This "searching" is what causes the weird lighting issues.

Obtain some 1/2" braided strap, a hand full of blue or yellow terminal eyes, and some #8 sheet metal screws. Cut the strap into various lengths and crimp AND solder an eye to each end of the pieces.. Using the sheet metal screws, connect a strap between the negative battery cable and the core support. Connect a strap at the rear of the passenger side head and the firewall. On each side of the cab, connect a strap between the floor and frame.. Do the same with the bed -- one on each side.. Remove the taillight assemblies and clean the ground wire terminals that attach the light housing to the sheet metal.. Do the same process at the front turn signals.. Locate the ground wires on the head light plugs and clean them also. Sand the area where the ground is attached, exposing bare shiny metal.. Apply a small dab of grease to prevent rust... This is a lot of work but it will ensure you have proper grounding for the light system..

 

[Craig Nedrow]

When I disassembled my truck, I was surprised at how many grounds were on it, two in the engine compartment, two on the cab, and one on the bed in back. I like Rustypile thought process.