backup lights not working

[Chevyboy1962]

Hey Gang,
I don't know wehre to really post this question, but I hope you guys could help me with it.
I finally got the backup lights hooked up, but the lights are not coming on. The switch i'm using is a 3 prong switch that lights up when it's turned on. The temporarally switch lights up, but not the backup lights. I can only think of a couple things that is causing them not to come on.

The first one is that the connections in the main tail wire harness (runs from cab to rear bumper), it has the extra wire for the backup lights. The second one is that I do not have the wires plugged in properly into the switch. Or three, the light switch itself is the wrong one to be using (the last 2 I dought).
What do you guys think?
Many thanks,
David

[Chevyboy1962]

Fixed it.
I touched both wires together, and there was light. 5 mintues later after kept plugging the 2 wires in different combos, I finally found the right one.

Here's a pic.
backup light

[71Blazer]

It's always nice to see where you are going, even if it's backwards.

[Hook'em]

Back-up lights are the next project after I get my A/C fan to work. I don't even know where to start. I assume they worked at some point, because they have good bulbs. I guess I need to check the wires all of the way back. Would a short cause both lights not to work or do they run on different wires?

[Longhorn Man]

They run on one single wire...dark green if memory serves.
Best first place to look is the fuse obviously, but then the switch. On an automatic, it is at the bottom of the column with the netral safety switch, it is the one with the green wire on there, the purple wired plug is the neutral safety switch. Check for power going in, and then power going out of the switch. You can make a jumper to see if the lights come on.
After that, if all checks out, I would skip the whole underside, and go straight to the rats nest under the bumper. Onless you are lucky...or rewired it...then there has probably been 5 or so trailer harnesses installed over the last 30+ years. Look to see if the wires are buggared up, and repair what ever you find.
If you still have nothing, then follow the harness untill you find a messed up section.

If you have power to the wire all the way to the bulb, but still no light, then you have a ground issue.

[Hook'em]

Thanks for the comprehensive reply, Longhorn Man. I keep printing these threads out, b/c there is no search function. I am amassing quite a book.

[Longhorn Man]

lol, you'll need a search to go through your hard copys!