Troubleshooting No Left Blinker or Brake Light on Trailer

Question:

plugged in trailer no left blinker or brake light with 2003 Ford Expedition

asked by: Dave

Helpful Expert Reply:

If you brought your truck and trailer into my shop, I'd immediately check three things and in this order:

1. Corrosion or dirt/debris on the 9 o'clock pin in the trailer connector on your tow vehicle and on the 3 o'clock pin on your trailer side plug and clean/replace as necessary. I like to use a circuit tester like part # PTW2993 on the 9 o'clock pin on the vehicle just to make sure I'm actually getting a signal. No signal on the vehicle side connector could indicate a fuse issue.

2. Check the left turn signal/brake light fuse. On your 2003 Ford Expedition, this fuse is in your passenger compartment fuse panel. There should be a 10-amp fuse in slot 42.

3. Check the wire between your trailer connector and your left tail lamp assembly on your trailer for any cut, frayed or pinched sections that could be causing a short.

If you check those three things and you still can't find the problem, let me know what you come up with and I'd be happy to help you troubleshoot further.

expert reply by: John H