Troubleshooting Trailer Wiring on Trailer Pulled by 2000 GMC 1500

Published 02/26/2015

Products Featured in This Question

Draw-Tite Activator IV Trailer Brake Controller - Up to 4 Axles - Time Delayed

(357)

$103.31

7- and 4-Pole Trailer Connector Socket w/ Mounting Bracket - Vehicle End

(2636)

$43.13

Hook Probe Circuit Tester

(60)

$12.27

Question:

I had a drawtite trailer brake on my 2000 gmc 1500....the plug it self is a 7 round...it had a round to flat adapter plug in it that was all corroded I removed the plug and it started to smoke inside the receptacle.....I cut feed wires going to the booster module so it wouldnt cause a issue....found where the module plug was plugged into the junction box under the dash.....I still do not have a driver side running lites .....all other lites work fine....the 7 wires are still tied into the harness....if I cut these will this solve my issue of no marker lites

asked by: William

Expert Reply:

Is it the marker lights on the truck or on the trailer that aren't working? I believe the corrosion in your 7-way to 4-pole adapter caused something to short out, which probably damaged your trailer connector. I'd recommend a replacement like part # HM40975.

If the malfunctioning running lights are on the truck, check the fuse box under the hood next to the battery. The lid of the fuse box will have a diagram showing which fuse protects which circuit.

If it's the trailer running lights that aren't working, on the driver's side, the problem is likely to be found in the trailer wiring. Trace the running light circuit, which is usually a brown wire. Begin at the trailer connector and follow the circuit back to the running lamps. Look for any pinched wires or wires with cracked or worn wire insulation that would allow the copper conductor to short out on the trailer frame.

I'll link you to our Trailer Wiring and Trailer Connector Troubleshooting FAQ articles.

expert reply by: Mike L