I am adding a brake/cargo light from a 97 Silverado onto my 89 Silverado that has no 3rd brake light. The wiring plug from the 97 has 4 wires, 2 white, 1 blue with white stripe, and 1 black wire. I guessing the black is ground and the blue/white is to the switch for the cargo lamp but that leaves me with the 2 white wires and I don't have the brake light part wired. HELP PLEASE!

 

I would take the bulbs out of the 97 unit and check for continuity from one wire end to a contact in the socket. Do them one by one until they are all identified. Then you will know which wires go where.

 

Ok, I will give that a try and let you know. Thanks for your help.

 

Wondering if any Chevy truck guys could help..I have a 97 C1500 and I purchased an LED 3rd brake light and I installed it, plug n play deal, no problem but when parking the truck,(engine off) the delayed inside overhead/cargo light goes off after a few seconds like it normally always does but now the LED 3rd brake light comes on in a running light mode (Not bright like it would be if you put the brakes on) after being completely off..This truck comes with the over ride button an needless to say I tried many different combos trying to get the 3rd brake light to stay off while the truck is parked.. Any ideas or help would be appreciated