Hi I am new to yota tech. I just bought an 89 Toyota pickup 4x4 standard cab with the 22re. The truck only has 40,000 miles but I am having some light problems. The brake lights work when the headlights are off but at night when I turn the headlights on the brake lights are on instead of tail lights. When I step on brakes the front side marker lamps come on when brake pedal is pressed. Where do I start trouble shooting this? Any help would be appreciated. Thanks

 

If it has a trailer hitch, check to see if it's got the trailer harness (usually 4 wires) and plug hanging out in the back. I've seen them get frayed or shorted to each other causing weird lighting issues like the one you're describing. If the wiring looks good from there, then it could be where they tapped into it in the vehicle.

Another question I'd have is does this happen ONLY with the headlights on or does it occur also when you only turn on the parking lights?

 

I had a somewhat similar problem, when I would step on the brakes the front marker lights and the dash lights would come on. It turned out to be the trailer wiring installed by the previous owner. Start looking for wiring that isn't factory, and making sure it is working properly.

 

Had that exact problem with the s10 I had b4 gettin my yota pickup! Check your grounds near the back! Mine had 2 and one was broke off causing the weird lighting issue

 

I had a similar prob. turn parking lights on, brake lights lit up. step on the brakes and dash lights and marker lights came on. I checked the trailer wiring and found no broke wires. So I cut the trailer wiring out and all works perfect.

 

Yes, check for a trailer wiring connector. Without the proper converter box (5-wire to 4-wire) that could be the problem. And check for the proper (1157) bulbs in the tail/brake light socket. They must be a dual filament bulb, sometimes folks jam in a single filament bulb and then you can see that behavior. And if that is all good, then check the ground connection for that bulb. I have had similar issues with my VW where the common ground connection is missing and then one filament can ground through the other filament. All is fine as long as only one is on at a time, but turn on both and then there is no light:
- http://www.4crawler.com/Diesel/Cheap...#SocketRepairs

 

To answer one of the questions this happens when parking lights are on and headlights. No there is not a trailer wiring harness. I am going through everything. Thanks

 

Also try removing both brake light bulbs then put back one at a time and see if it may be one of the bulbs that is causing the problem. Bulbs can be shorted internally and cause that sort of problem. And make sure both bulbs have two metal contacts on the base, not just one in the center:

1156/single filament:

1157/dual filament:

 

I finally went out and messed with the wiring and I did find what was left of a trailer harness a bunch of frayed wires with no harness. I think I got everything working right. Thanks for all the help.