I've already searched and didnt find any info regarding the problem that I am having. Since I've owned the car (M6), the reverse lights never worked. I am now trying to get them working. Here is what has been done already:

1. Replace reverse light switch on tranny. No lights.
2. Light bulbs both good.
2. Multimeter continuity test on the rear harness (unplugged from the main harness at the back of the car and tested from the plug to the light bulb sockets. light green wire, both lights good.).
3. Key on; disconnected the plug from the reverse switch on the tranny and jumped the connector to bypass the switch. No lights
4. Key on; measure voltage from the plug at the tranny. Nothing.

I almost think the problem is before the tranny switch. I checked shbox and cant find a schematic specifically for the reverse lights. I see that the light green wire at the reverse light switch routes up and into the harness at the top and back of the engine and goes in the direction of the PCM. I traced the route of the wires from the back of the car as far as I could without completely taking the car apart and they go inside the car along the drivers seat, then disappear under the carpet (not sure where they go from there). I guess I am trying to find the missing link here. Any help from you guys is appreciated. I havent driven my car in months because I need an inspection, and this is the last thing I need fixed before I can drive it.

 

This is a very simple system. One brown wire from the fuse box, (you did check the fuse??), Turn B-U Fuse #2, 15amps, to the reverse switch. One green wire from there to the rear body harness where it splits into two and goes to the lights. Then of course two black wires to ground.

The manual says: "Check for a broken (or partially broken) wire inside of the insulation which could cause system malfunction but prove "GOOD" in a continuity/voltage check with a system disconnected. These circuits may be intermittent or resistive when loaded, and if possible, should be checked by monitoring for voltage drop with the system operational (under load)."

There is at least one splice under the RH dash and some connectors before the trans. switch. Your just going to have to trace this wire run.

 

I figured it out. It was two issues. Brown wire somehow got cut so it didnt show voltage when I tested it at the reverse light switch. Once I spliced it, I tested it at the switch and it was good. 12.3 volts. Plug it into the switch, put the car in reverse and turn the key on. Nothing. I get back under the car pull the plug jump the green to brown wires. I get lights. Wife is behind the car and when I plug it back into the switch she says the lights come on. then off. I push on the connector while it is plugged into the switch and they come on again. I let off, and the lights turn off. Pull the weatherseal off of the plug and tape that connector down tight onto the switch and everything is good now.