Troubleshooting Trailer Lights Not Working When Connected To 1994 Ford Ranger That Work With F-150

Published 08/11/2017

Products Featured in This Question

Hopkins Plug-In Simple Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

(56)

$41.35

Dielectric Grease for Electrical Connectors, 2 oz.

(1481)

$10.94

Question:

Had a buddy hook his Ford F150 up my 10foot cargo trailer, everything worked great. My Ranger when hooked up...trailer...no blinkers, tail lights work only very intermittently. My regular auto mechanic said truck plug tested as good??? 1994 FORD RANGER XTRA CAB 4FLAT PLUG TRAILER HAS INCANDESCENT ST70RB STYLE LIGHTS-3 FUNCTION STYLE 4 FLAT PLUG Any help would be great!

asked by: TONY D

Expert Reply:

Because your Ranger has tested good and yet your trailer does not work correctly when connected, there is a really good chance that it is a ground issue. This could be on the vehicle side, but is more likely to be on the trailer side. A faulty trailer ground could still work with a vehicle that puts more power into the trailer, so your friend's F-150 working doesn't mean that ground couldn't be faulty. I recommend checking that ground for rust and or corrosion and cleaning it up. You want a bare metal to metal connection.

If the trailer ground is not at fault, then I would check the ground connection on your Ranger pickup. This also needs to be a bare metal to metal connection without any rust or corrosion.

Also check the actual trailer connection and add a little dielectric grease # 11755 to help that connection. Finally check the ground wires to the lights.

If that doesn't solve your connection issue, let me know and we can continue to troubleshoot.

expert reply by: Jason S