So this might be a bit out of the norm. I am doing a 350 Chevy swap into my sons 1983 FJ-60. The motor is a 1987 out of a GMC van (I know, probably not everyone’s first choice but I have to play with the Colorado emissions standards). The transmission is an older model 700R4.

To the meat of the question. The Toyota wiring harness had a four wire plugt hat went along the frame and plugged into the transmission if I recall, sorry the swap has taken longer then I thought it would. One wire is a white black I think is a ground. One is a yellow black that I have no idea what it is. One is a blue and if I power it sends power to the dash. The fourth is a red blue (?) that turns on the right reverse light.

What should I do with these four wires? Why does only one reverse light come on? I have a four pin plug in the 700R4 that is incorporated into the GM harness but I am not quite sure how the 700R4 activates the reverse lights.

Any help would be appreciated.

Might want to check the other reverse light bulb and socket for issues.I wish I had books that go that far back. You might have to hit a Toyota site and see if there is any help in the way of wiring diagrams.Anyone else take a crack at this?

Ya, I checked the bulb and socket. No continuity between the sides. Maybe I have a short somewhere between them. I looked around a little on Ih8mud but couldn't fiund an answer to my specific question.Thanks though Mike