GM-GMC: 1997 K2500 back up lights not working, pink wire, test light

Question
Hello,
I am the new owner of a 1997 K2500 Cheyenne pick up truck.  The back up lights are not working.  I have checked the bulbs, and they are fine.  All other lights are working fine.
I would assume it is either a bad wire, or the switch.
Hope you can help.
Thank you,
Pierre

Answer
Check terminal F of connector C1 of your transmission range switch, it it a LT GRN wire.  It should light a test light with the truck in reverse.  Block the wheels and set the park brake, engine OFF.  If it does light the test light than you have a wiring issue between there and the lights if not.  Check for power coming into the switch at terminal C of the smae connector should be a pink wire and have 12v at all times.
Hope this helps.