Flaky Tail Lights

[Rad64]

While not a truck per se, my 2005 Tahoe LS is acting strange because all of the lights work accept the tail lights at night (only). The brake lights work, the backup lights work, the turn signals work, and the tail lights will work during the day if you force the lights on. However, sometimes, the tail lights/license plate light won't work at night but all of the other lights work. I've replaced the light control switch and nothing changed. The bulbs are new and I've check all of the fuses. I'm at a loss...

[Jsdirt]

This screams of a poor ground. With the headlights on, they are using up what little grounding is available, I'm thinking.

 

Try rigging something up so you can provide a ground to the tail light using a length of wire. I raid my wife's knitting supplies for T-pins - they can be slid down into a weatherpack connector along the ground wire to make contact inside. Since you're in AL, presuming the truck was originally sold there and has spent most its life there, you should have no problem finding a suitable ground on the frame, or a bolt head nearby. Up here in the Northeast, we'd have to go straight to the battery negative due to excessive rust. Check the ground location with a test light to make sure it's good, before checking the tail light with the headlights on. if you suddenly get a working tail light when you touch your rigged up wire to ground, then that's the problem - a bad ground. From there, you can either chase the ground wire and look for an open, or bad connection, or splice in a new ground to connect elsewhere.