Troubleshooting Trailer Wiring with No Tail Lights when Running Lights Function Correctly

Updated 01/15/2018 | Published 01/13/2018

Products Featured in This Question

Hook Probe Circuit Tester

(62)

$13.33

16-14 Gauge Butt Connector - 5 Pack

(31)

$4.30

16 Gauge Primary Wire - Black - Per Foot

(62)

$1.14

Question:

I have running lights but no tail lights

asked by: Gregory J

Expert Reply:

Running lights and tail lights are functions on separate wires for your trailer. I recommend you check your vehicle fuses and then test the wire functions at the connector using a circuit tester like # PTW2993. If the functions work correctly there, then trace the wires using the probe to locate the short and replace as needed with # 16-1-1 sold by the foot and # 05731-5 connectors.

If you mean that you aren't getting the running lights at your tail light location, then check the ground wire on your lights for a clean metal to metal connection free of rust, corrosion, or debris. If you have incandescent bulbs, make sure to check the bulb itself for function as well.

I've attached a wiring diagram to assist in troubleshooting.

expert reply by: Jason S