So ive got a 1991 pickup with a 3.4 swap, and i cant get the damn reverse lights to work!! I looked at the schematic and followed it. I tested the 10A GAUGE fuse, tests fine. I tested for power at the connector/backup light switch with the key on, not getting it on either side, and so obviously im not getting anything at the light either. Im thinking that im missing the reverse light relay. Where is it located on the truck?? Any other ideas or suggestions ?? PLEASE HELP. I just replaced the switch today and still doesnt work.

 

Well, that is a head scratcher. No power to the switch, and replacing the switch didn't somehow make it work?

My '93 EWD says that only the A/T models have the Backup light relay. The power side to the switch should be Black-Orange. On the A/T models that wire is powered from the CIG fuse, on the M/T models it is powered from the Gauge fuse. The Black-Orange is powered with ACC on A/T, key-on with M/T (the relay is downstream, so if you have no power to the switch, it's not because you're missing a relay.)

My '95 EWD says the B-O wire is powered through the Dome fuse, and there is no backup relay at all.

Of course, if you have a 3.4 swap you've got mostly replacement wiring, and I can't tell you anything about what was installed (or not installed) in your truck.

Before I wasted too much time on this, I would run 12v to the OTHER side of the switch; the color of which varies all over the place. If 12v to other side of the switch lights up the back-up lights, you're ready to figure out why you're not getting power to the B-O wire.

The Relay is in the top of J/B 1 (left kick panel). But as I pointed out, if you don't have power to B-O, the relay is not your problem.

 

Something missing or not hooked up from your swap.

Good idea to change the switch when your not getting system voltage to it.

Maybe changing the back up light bulbs may help in the same fashion.

 

No the fuses, switch, and bulbs are all good. Like you said somethings not wired up right. So what i did today was i took the old harness of A/T connectors that the PO left hanging. 1 of them still had ignition voltage so i butt spliced that wire (not sure what it went to) to the switch connector. Now my switch has 12 volts! so now all i gotta do is buttsplice the wire running to the lamps up to the other side of the connector and i should be good. Ill let you all know once i get that done.