Troubleshooting Trailer Wiring with 5-Way Connector on Truck and 4-Way on Trailer

Published 01/23/2018

Products Featured in This Question

Hook Probe Circuit Tester

(61)

$13.33

16 Gauge Primary Wire - Black - Per Foot

(61)

$1.14

Question:

I have a 1998 k1500 and my trailer plug wires broke and Im not sure where they all go to I have 4 to 5. 5 on truck. Color of the wires on truck are white, yellow, brown, light green and dark green. On the plug I only have yellow white brown and dark green. Its messing with my taillights and I cant figure it out

asked by: Daniel W

Expert Reply:

With the 5 way on your truck in non-standard colors and the 4 way on your trailer also with odd colors, you will need to use a circuit tester like # PTW2993 to determine function. I recommend testing your truck for functions first when disconnected from trailer and then using a battery to test your trailer individually as well. If all checks out, clean your trailer connections and test together. If the issue is on the trailer, first check your ground wire for a clean connection that is bare metal to metal. Next check the trailer lights to see if they have a separate ground and if so clean those ground connections. Finally if the issue is still there, trace the wire or wires at fault and find the short by probing the insulation on the wire every few feet. When short is found, replace the wire as needed with # 16-1-1.

I've attached an article with a diagram of trailer wiring to assist.

expert reply by: Jason S