Hello everyone, I have a 2004 f150 fx4. My running lights on my trailer will not come on. Brake lights work, turn signals work, back up lights work. Had my boat mechnanic check the trailer and that showed that the lights work fine. So I started checking fuses on the truck. Fuses all looked good. Then I went into the Auxiliary Relay Box in the engine compartment on the left fender. In the spot marked Trailer Tow Park Lamps (R201), theres no relay. R202 is for the Fog lamps, same relay. I pulled the Fog Lamp relay out and went to put in R201 for Tralier lamps, but theres no contacts in the R201 slots. The relay goes in with ease and just falls out. No contacts. Whats going on? Help me!!

 

Running lights should work with tail lights. If you pull your light switch to first stop, the tail lights should be on, both on the truck & trailer.

Don't know if your trailer has second wire for running but needs to be connected to work with tails.

You may need to make a change at the connector.


John

 

Had the same issue on my 2004...a connector at a wiring block wasn't quite pushed in all the way from the factory...follow the harness from the bumper back and you'll find it.