Assuming I test for voltage at the bulbs and find none, what to check next?

Which fuse is it and where is that located? Should the fuse have power only when the ignition key is ON?

Is there a relay and where is that located?

Is there a reverse switch on the transmission or gearshift and where is that located? How do I test that for power? If the switch is hard to access, how do I test the wiring remotely to verify the reverse switch works?

Where can I view the wiring schematic?

 

The circuit has both a back up switch and several fuses. Each back up light is 21 watt. The black wires go to ground very ground is ok visually. The green and black wires come together and then hit the back up light switch. There is a color change in the wire here going from green black (stop) to green yellow heading to the switch. The switch is on the transmission housing and should be closed in "R". the other side of the switch is yellow wire. The yellow wire heads up under the dash to the under dash fuse block. Found by the drivers left knee the fuse is number 5. It is 7.5 amps. The othe side of the fuse block is black yellow and heads to ignition. So Ignition on for testing.

Utah

 

Thanks for the wiring diagram info! Exactly what I needed! I could raise the car and check the reverse switch but since I'm lazy and a friend borrowed my ramps I should check fuse 5 and if I remove it I should find one contact (in the fuse holder) gets +12v key ON and the other contact gets ground (through the bulbs) with the shifter in R. Right?

 

Correct

 

I found a black switch on the left side of the transmission with a 4-wire connector on it. Further above that, are 2 other connectors that are near the top of the transmission. I found a wire coming from the same harness with just 2 wires and they're cut off. Green and yellow wire. Probably for the reverse switch. Any idea where is the reverse switch?

 

Back up is a 2 pin not 4. The cut wires will be for secondary O2. The other half of the cut Y is connected to the back up switch. With car in reverse there should be continuity between the two pins. Hope it's not the switch as you have to lower the tranny to get to it.

Utah

 

The other half of the cut Y? Sorry I don't follow. Can I post a picture of what I see under the car?

 

The other half of the cut Y? Sorry I don't follow. Can I post a picture of what I see under the car?

 

Thanks, Utah, for the replies. I still haven't heard back from you so I don't know what a "cut Y" is. But, I checked the internet for a parts diagram of the reverse switch and got under the car again today. I need to clarify on some points you made: 1) the reverse switch is on the right lower side of the trans. I saw it today and it is easily replaced by a socket without removing any parts or moving the trans. So that is good news. 2) My switch works. There is continuity between the 2 pins when trans shifted to R. Good news too. 3) The reverse switch has a pigtail lead that routes over the top of the trans and a connector on the driver side of the trans, within easy reach. The wiring harness has a mating connector there. My harness connector was there but no wires coming from it. So, the two loose wires (green with yellow stripe) that I mentioned before are for the reverse light. I shorted them to each other and the reverse lights came on (ignition key on). More good news. The repair is to connect the loose wires to the connector by installing the missing connector terminals. Found the whole connector at local auto parts store for $32 and on line used for $20. Hope this info helps someone else out there.

 

Sounds like you figured out how to fix it. Glad to be of some help. Congrats!

Utah