Reverse light connector

[86aggie]

My backup/reverse lights aren't working. I rolled underneath and found this plug hanging loose on the passenger side of transmission between frame and trans. Is it what needs to connect to switch on transmission for reverse lights?

 

[Steve83]

Post the wire colors, and the year/model of the truck.

 

[86aggie]

I finally got under the Guse today, to replace the shackle bushings. I wiped off the two wires coming to the plug and they are yellow with a blue tracer and yellow with a green tracer. I looked thru the 84-90 wiring diagram I have, and the only time I saw that combo was for the heater blower. I used my heater one morning a few weeks ago, and it seemed to work fine, so I'm thinking that is not the answer. I also wouldn't expect a plug for that to be next to the transmission, near the firewall. There is only about 3-4 inches of wire/plug after it comes out of the loom.

Any ideas?
Thanks

 

[Steve83]

On p.3 (zone 10A) of the '88 wiring diagrams I found on Google Images, those colors are used for the t-case neutral indicator light.