Back-Up lights I have just had my Envoy worked on and when I put it in Drive The back-up lights come on.When I put it in reverse lights go out.I know it a connection problem but I don't know where the wires connect.I think its under the shifting lever but not sure.Could use some help,. Thank You!!

https://www.transmissionrepaircostguide.com/topic/no-reverse-2002-gmc-envoy-slt
http://www.fixya.com/cars/t13849301-03_gmc_envoy_will_not_go_in_reverse https://gmtnation.com/forums/threads/2003-trailblazer-ext-wont-move-when-engaged-in-drive-or-reverse.9590

Rock back and forth might help. Drivetrain might be wound up in hard surface. Reverse in 2WD for 29-39 ft and try to shift to AWD.

Here's a link to the back up light switch. Repair Guides Manual Transmission Back up Light Switch AutoZone com Here's the part. Duralast Back Up Light Switch JA447 1995 Nissan Datsun Pickup 2WD 6...

Just to confirm, you don't have an electrical 4WD selector; you have to move a shifter on the floor of our cab? If that's the case, I'd suspect that you have a linkage misalignment or malfunction that doesn't allow the 4WD selector to completely return to the 2WD position. Putting the truck into reverse and back to drive probably causes a jolt to the 4WD linkage which disengages the transfer case from the driveline. Check for slack or binding in the transfer case shift level linkage (clean and lube the linkage won't hurt).

Sounds like the pump is going bad inside the transmission.

You could also have a leaking seal when the transmission heats up enough to expand and leak. That or if the electronics controlling the transmission are getting excessive resistance do to a short, that could also cause the problems you are describing.

check the neutral safety switch. connected to the shift lever, keeps you from running the starter unless in park or neutral, AND it turns on the back up lights when in reverse.

it sounds like ur rack in pinion is getting 2 go out

You most likley have a bent/damaged shifter cable. Unhook it at the trans, and move the linkage, with the park brake set. Push it all the way forward, that is park. The display should change and it should start. If so you will need the cable. Good Luck

the reverse clutch has failed in the transmission, this will require the trans be torn down for repair.

Advice only: DO NOT DRIVE have towed to transmission shop. Had jeep do this once...don't risk it?