I had an 84 that had this same problem... I'm sure that it is a ground related problem, but I never was able to track it down.
I went as far as to pull then entire body harness out of the car and checked it over thorougly. I was unable to locate anything that would have caused this.
Rather than put the original harness back into the car, I chose to find an 84 in a local wrecking yard to put back into my car. This did solve the problem, but was rather extreme.
On the bright side, I probably had the nicest wired Supra on the road.
Anyway... Good luck and I hope that you have better luck finding it than I did.
I had a similar probloem in a Fourunner, right after we replaced the fuse junction with one from a different year truck. Totally different vehicle, but maybe you could start there? they are set up somewhat similar. (Im talking about the fuse junction inside, behind the kick panel by the driver's left foot
Ahh yes...the kick panel. That has been jury rigged by a previous owner and has relays hanging every which way. I agree I think its a ground. I also just noticed that the front park lights also light up when I step on the brakes. Its possesed :twisted:
Thanks for the help