hey there - my 99 4wd TRD Taco has the dreaded and well known issue of blowing tail light fuses for the last few weeks. I thought I had found the problem short 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

 

I would start with rechecking your tape job.

Look at those wires see if they are rubbing any place .

I would guess your short is in that area .

Unless you had the short before you took out the light.

Does the fuse open as soon as you turn on the circuit??

Or does it open at random times??

 

thanks - first thing I did actually was trim the wires back a little more and retape them - then I checked along their visible length for any abrasions etc... it definitely seems like the culprit should be there somewhere - is there any way to isolate that circuit back at the fuse block?
and should BOTH of the wires have continuity to ground? I'm thinking only one should yes?

 

FWIW - 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

 

Glad you were able to find it .

So it was just a random thing unrelated to the front damage.

You should really try and get a copy of the EWD for your truck these newer ones have so many things your really lost without being able to look at the prints.

 

EWD? is that "Electrical Wiring Diagram"?
just a guess...

actually I managed to find a wiring diagram for the tail light circuit, and for everything else...
unfortunately it wasn't very good at telling me the physical location of anything so I had to do a little bit of googling to find the BN1 connector.

 

What is nice the EWD`s give you the locations of all the goodies.

The connections

The ground points

The relays and sensors.

Getting the one for any new Toyota is the first thing I do

 

so - it is a wiring diagram? but not the same one found in the service manual?

 

It is a separate book that is part of the factory service manual set if you buy the complete set.

Then it also could be bought alone.

Since Toyota Sold all the Factory Service Manuals below the 2000 Model year To Helm Inc prices have more then tripled .

Then if Helm feels there is not enough demand they no longer print them.