Weird light issue

[SixPointTwo]

My interior lights have never worked...check the fuse and its blown. Put a courtesy fuse in it and the interior lights work. Great. But, now when the door is closed, the third brakes turns on even with the truck and lights off...open the door and the courtesy interior lights turn on and third brake light turns off...had to pull the fuse again to keep it from draining my battery....why would this happen???

 

[twomanymontes]

Sounds like you have a short in the wiring between the 3rd brake light and the cargo lights if your truck has them. The dome/cargo lights are powered all the time and the door jamb switches make the ground connection. I can't access a wiring diagram at this time, but there are a few connectors in the circuit, a little bit of corrosion could be connecting the 2 circuits. Hope this helps

 

[SixPointTwo]

Do you know where the connections are in the truck?

 

[twomanymontes]

Sorry, Can't seem to get any wiring diagrams on this computer. I will see what I can come up with on Lunch tomorrow at work and reply tomorrow evening.

 

[BoxerPitMix]

I would start out by pulling your 3rd brake light out as well as your dome light and just check for bad connections/corrosion in case any water got in.

The next place I would check would be the harness coming back from it. I'm not 100%, but I think it runs under the plastic door sill panel on the driver side. That's a bad place to run a screw threw a wire when you're screwing those panels back down.
I'm sure someone else here that knows better than me will chip in.

 

[twomanymontes]

I checked out the wiring diagram. And The only connector they have in common is the one under the dash. But the wires do run in a harness under the carpet and to the door sill, then up the left post across the roof to the light.

Under the door sill it collects lots of dirt and moisture, the wires may be shorted together there. Also check the back of the 3rd brake light for water intrusion.

 

[SixPointTwo]

Hmm okay I'll check it out, thanks!

 

[pewterz71]

did you ever figure this issue out with your 3rd brake light? I'm having the exact same issue right now and its driving me nuts!

 

[SixPointTwo]

No I didn't, I just unplugged it