Back-up lights don't come on

[Vegasli]

I own a 2003 Chevrolet Trailblazer EXT.

When I put my car on reverse back-up lights do not come on. I checked the fuse box in the engine compartment & changed the light bulbs, but the problem still exist.

What else can I do to fix this problem? Thank you & have a nice day

[maxwedge]

These issues can be simple as bulbs, but if not then it can get tough, not 100% sure here, but I believe the trans range switch sends a signal to both bcm and pcm and the bcm commands the bu lites, without a real wiring diagram , tough to tell. I assume you checked for 12v and ground at the sockets. Alldata.com has complete online manuals for 25.00 for 1 year access.

[rodeo02]

Didn't the 2002-2003's have issues with the lamp holders/sockets for the rear lense assemblies? Hopefully it's just that. A quick check for a functioning trans range/mode sensor is watch the PRND321 dash lights. If they flicker, flip around at random or dont line-up with what you selected with the floor shifter, you've got a range sensor issue. I believe it's internal to the trans on the 4L60E. A bad range sensor will make the trans shift in failsafe mode which will give harsh shifts.

Joel

[edbrycem]

I think that light issue was primairly for the brake lights not working.......I could be wrong though.

[maxwedge]

Correct, but it is possible the bu lites could be affected hence the prior suggestion to confirm 12v and gd at the sockets.