The tail light fuse on my '90 Toyota 3.0L 4x4 keeps blowing out. I checked the wiring harness underneath the truck all the way to the tail lights and trailer harness. All the wires were fine. So then I unhooked the harness, where it connects, underneath the passanger seat. Tested again and still blew the fuse. In addition to the tail light problem, it has also made it so my insturment cluster lights won't light up either. So I'm thinking the problem has got to be somewhere in the cab section of the wiring. If anyone has an idea of what might be causing this please let me know. THANKS!

 

Try disconnecting the trailer light harness and see if things change. If not, check the tail light bulbs, might be the wrong type bulb or one with an internal short.

 

Not that this matters but - when you say tail light fuse, does it blow within a minute of replacing it with the car on? Or only blow when you say, hit the breaks, turn on the "lights" or use reverse. Blinkers? I guess I am trying to see what "Draw" is blowing it.

Edit...4Crawler hit the nail on the head, the wrong bulbs would "draw" too much power and blow a fuse!

IIRC ~TC~ had this problem in his 93 runner, but for the life of me I can;t remember what we did to fix it.

I hate electrical fuse gremlins!

 

I had this issue and it was an old shorted trailer wiring harness. I redid the harness and no more shorts.

 

Already checked the bulbs and disconnected the tail lights completely. Fuse blows when truck is running or off and only when I turn on the lights (i.e. parking or fully on). I don't like electrical problems.

 

I had the same problem it was the tail light relay by the fuze box in the cab. round metal silverish lookin thing. i'll take a pic 1 sec.

 

im pretty sure it was the one on the top left. its been a few months so im not sure. they are like 20$ or u can pull one at a junk yard and hope it works too. hope this helps

 

Thanks for all the help everyone! It was nice to get some fresh ideas. The issue ended up being the illumination wire for my stereo. It was grounding out and blowing the fuse. Just goes to show that electrical problems can come from anywhere. Problem solved!
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i am having the same problem on my 91..only not blowing fuse. The previous owner of my truck had the cd player stolen and they cut the harness completely. Do you think it would be the dimmer switch grounding out to cause this problem.?..mine were working fine until i spliced into the right parking light btw

 

I'm thinking my truck may be the trailer as well. Pain in the ace!