persistant tail light fuse blowing... need help tracking short

hey there - my 99 4wd TRD Taco has been blowing tail light fuses for the last few weeks. I thought I had found the problem in some wires that were just hanging after a fender bender I had took out the front passenger turn signal (corner one). I trimmed them and taped up the ends and it seemed like the problem went away at least for a couple of nights - now however it's returned and I can't seem to find the short that's causing it.

I've switched the relay and had the same problem so that's not an issue.

one thing I noticed is that there is continuity from one side of the fuse mount to ground - and that just doesn't seem right does it?

it would help if I had a wiring diagram... anyone know where I can find one without buying a manual?

anyway - if anyone has some trouble shooting tips for tracking down a short in this system - or in general - I'd appreciate it.

oh - and BTW, I don't have a tow package or an alarm system and I tried disconnecting the license plate lights (which oddly had continuity to ground from both wires?)

cheers,
bennett

 

On my 96 reg cab the rear harness has a plug under carpet driver side. Did you check plug connections there. There are 3 or 4 semi open areas in my harness. Wires run threw guides and lightly taped. Exposed wires in these turns. I have the harness in my hands right now,so if you have any questions maybe I can help.

 

I'll start with the most basic question. Did you try a new bulb? I've had bad bulbs blow fuses on my vintage motorcycles.

 

yeah, replaced the bulbs a while ago...

FWIW - I fixed it.

the problem was the small remaining (previously unnoticed) tails of a tow package... the same culprit as in 90% of other cases - I didn't notice the wires because they had been cut very short etc etc

the big clue was that the green wire was getting continuity to ground but when I disconnected the BN1 connector (when I finally found the damn thing!) the short at the fuse block went away - thus the problem had to be in the rear section... lic. plate lights were ok so it had to be tail lights.

QED


NOTE - for others experiencing this issue, the BN1 connector is found under the drivers seat - it can be accessed by unscrewing the skid plate in the door sill and lifting up the carpet.

 

thanks for the offer of help Andy!

 

No problem Bob. I had similar problem years ago and found harness connector out of necessity. Surprising what you can find under your seat sometimes.

 

Yeah - the tow package wiring seems to be the culprit in almost every case. I was thrown off by the fact that these had been trimmed pretty short and were camouflaged by the tangle of taillight wires on that side. Also by those exposed wires in the front.
Cheers.