Dash reverse light problem - Help!

[70sublime]

Ok guys, I'm relatively new to this forum - I need some help from the electrical gurus out there! Here's the situation: I have a 70 Challenger R/T restored. Originally an automatic car and was converted to a 4spd many years ago. The reverse light on tail panel works when car is put in reverse. No issues. I recently ordered a dash reverse indicator light and harnesses from Brewers. Installed the reverse light in correct location and everything else installed just fine as well. I also replaced the trans switch because it was old and leaking. The problem is this: the reverse indicator light on dash is on all the time after ignition switch is put to accessory or start. It doesn't matter if trans is in any gear or neutral, the light stays on. The reverse light on tail panel comes on in reverse as it should and goes out when taken out of reverse but the damn indicator stays on constantly. I know it's not the trans switch as the old one did the same thing before I replaced it.

I've reviewed the wiring diagrams and tried a few things to no avail. I'm stumped. The only thing I can think of is that there is some other hot wire that is providing power to that circuit constantly no matter what gear the trans is in. If so, I can't seem to locate it. ugh!

Any help is appreciated. Thank you!

Grant

 

[72RoadRunnerGTX]

What do you have it connected to? Should go here, near bulkhead connector, engine compartment.

 

[70sublime]

Thanks for the reply. Yep, it's connected in the right place. Cable runs from the trans switch to the bulkhead connector then from bulkhead it connects to a wire that passes through firewall to the reverse light in dash. Weird. As I said, the back up light comes on when put in reverse so I know the trans switch works ok, but I cannot understand why the dash light is always on?

 

[72RoadRunnerGTX]

The black and black with tracer wire terminals in that bulkhead connector are reversed, swap them around it’ll work correctly. The black with tracer wires should be in the upper (#7) cavity, the black wire in the lower (#8) cavity.

 

[70sublime]

Interesting. I'll give that a shot. I don't suppose there is an easy way to swap the terminals in the connector without having to cut wires and splice?

 

[72RoadRunnerGTX]

There is, way easy, squeeze the edges of the male Packard terminals a little with some needle nose pliers, pull them out from the back. Use a small screw driver to spread them back to there normal position, insert back into the correct cavity from the back.

 

[70sublime]

Piece of cake to do that with the terminals and everything now works! Thank you so much for your detailed explanation. You are the man. I think I'll reach out to Brewers and let them know about that connector wire change if they don't know already. So glad I joined this forum. Thanks again!!

 

[72RoadRunnerGTX]

They likely sourced the reverse light switch harness from M&H/Year One. Would not be the first time M&H has shipped an incorrectly assembled harness, so I have heard. Always a good idea to double check that terminal locations on reproduction harnesses are matching the factory wiring diagrams IMO. Glad to hear it was a simple fix.