Reverse Lights not working

[mickdavis]

Hi, I just got an 89 GW and I believe that I have addressed all of the things that would prevent it from passing inspection, except for the reverse lights. I have verified that the bulbs are good. My plan of attack on this is:

1) Verify continuity of the wiring from the connector to the lights.
2) Verify that the switch on the transmission works.
3) Verify that it is getting power.

Anything else that commonly goes wrong with these that I should consider first? Getting to the switch is a bit of a pain...

Thanks.

Mick

[Srdayflyer]

thats a good plan, i would check the trans switch first , just jump the 2 pins at the switch connector the b.u. lites should illuminate with the ignition sw in the on position

[tgreese]

Not a lot of experience with automatics, but IME it's most likely the switch at the transmission or the connector to the switch at the transmission. Both those parts suffer due to exposure: water, dirt, corrosion, etc.

I have not looked at the '89 wiring diagram - however, if the switch on the transmission is a SPST switch as described above (ie connect two wires together rather than one wire to ground), there should be a separate two-wire harness for the switch dropping down the firewall that plugs into the under-hood harness. If my mental picture is correct, you can disconnect there and bridge the socket to test the lights. This will both isolate the transmission-mounted switch and its connector (bridge the socket), and whether you have power to the switch at the socket (check with multimeter).

A look at the wiring diagram would be where I'd start. I'd expect the ignition switch supplies power to the under-hood harness and to the switch. Then there would be a single wire from the switch that goes back to the under-hood harness, and connects to the chassis-rear harness, traveling rearward to the lights and ground. Not complicated, but good to confirm before I started.

[mickdavis]

Thanks guys, will do. Yeah I have the complete service manual with wiring diagrams. Just wanted to check with those more knowledgeable than I am to see if there is something I'm overlooking.

[akguy09]

Check the housing where the connectors are for rust as well, back side of the connector of the tailight housing. That will keep it from grounding

[mickdavis]

Thank you all for your suggestions and help. I was able to get them working again. I did end up checking the switch first. Must have been either a bad connection or corrosion. After unplugging everything and plugging back in it works again...