98 extended cab tail light issue

[Dk4509]

I have a 98 extended cab that has Developed a weird electrical issue. My taillights (blinker and brake) work fine without the headlights switched on. When the headlights are on, the passenger side brake light and blinker are on solid. I assume I have a short somewhere, but am having some problems tracking it down. Any obvious points to trouble shoot?? I have changed the turn signal (multi switch in the column) switch with no luck...

 

[Uncle Gump]

Sounds like you should be looking at the rear lamp harness connector. You may find it's all corroded. I would do some testing on the vehicle side of that harness and ensure that what you see at that connector is proper. If so... it is somewhere in the rear harness/sockets/bulbs. If not... get out the schematic and look for a common point of failure.

 

[Dk4509]

Well, after acquiring the correct schematic, I was able to start troubleshooting instead of changing parts. Turns out the problem involved damage to the grounding wire that serves the right front headlight and turn signal. Chipmunks got in my engine bay and caused havoc chewing on a few wires to include ground wire. I’ve attached a photo. Damn chipmunks!

 

[Uncle Gump]

That will do it...

This further confirms the "bad grounds and poor connections" theory even further.

Just out of curiosity... did the turn indicator on the dash light up too? Maybe even front turn signal?

 

[Dk4509]

So as long as the headlights were off, the dash turn indicator (as well as the rear signal) worked properly. When then headlights were turned on, nothing worked on the passenger side, to include the front turn signal and dash indicator. I guess since I was fixed on the tail lights being so goofy, I never noticed the dim headlight until I put the truck in my garage.

 

[Uncle Gump]

gotcha… it was the thing that stuck out to you. My point is this... Had you have mentioned the dim headlight... both turn signals and indicator on... I would have said bad ground and not to check the circuits at the taillight harness. Typically the better you describe the symptoms... the better the armchair diagnosis you receive will be.

Glad you got it figured out.... hopefully they didn't cause more damage elsewhere.