Troubleshooting Trailer Lights That All Work With The Exception Of Running Lights

Published 01/11/2017

Products Featured in This Question

16 Gauge, 4 Conductor Bonded Parallel Wire - Per Foot

(239)

$2.47

Hook Probe Circuit Tester

(70)

$14.42

Question:

i bought a trailer and all the lights work but the running lights.. what could it be.. ?

asked by: Tim B

Expert Reply:

Using a circuit tester like # PTW2993, check the running light function at your connector on your vehicle. If you have the function there, then you have isolated it to the trailer. If you don't have function there, you have an issue on the vehicle side. Check your owners manual for fuses if this is the case as often there is a trailer running light fuse. If it isn't a fuse issue, use your tester to probe the wire to find out where the wire is losing connection and replace as needed.

If you have function at your vehicle connector, check the connection for rust, dirt, or corrosion. Check the ground on your running light signal to ensure there isn't corrosion and solid metal to metal contact. Check the wire for any noticable issues like a pinched wire, missing insulation, etc. Check your running light bulbs. Then if all that checks out, run a separate wire from the connector to the lights to see if a separate wire solves the issue. Replace wire as needed.

expert reply by: Jason S