I have a 97 F150 w/ tow package. I am renting a trailer which I need to be on the road tomorrow.
flat 4 pin
When I left the U-Haul place all my light worked on the trailer. Now only the running lights (headlights) work. The directionals and brake lights don't work on the trailer but on the truck. Where would the relays be? Is it by the Junction box in the left hand engine compartment? There are two there one has relays and fuse the smaller is piggy backed off the larger one and have a total of 5 relays in it. 4: F57B-14B192-AA (6156A31-B) and 1: FOAB 14B192-AA

 

First, check to make sure you are getting power to the trucks flat 4 connector when using the turn signals and or the lights on the truck.

Uhauls use their own 'special' wiring on their trailers and usually make you buy one of 'their' adapters to make it work.

As far as I know, the relays on the truck are only for the electric brakes and a battery charge line. Only used on the 7 pin connector.

Good luck!!

 

relays shouldn't be involved in this situation. i'd check the fuses in the power distribution box under the hood. your owner's manual will show you the locations of the appropriate fuses. if you have a 12 volt tester, turn on your turn signals and insert the tester into the 4 pin outlet and see if it "blinks" at you.

 

I did that. They aren't blinking at me The Running lights I get power there. But the other 3 are dead.

 

Like MitchF150 mentioned above, U-Haul trailers may have a special adapter. I remember renting one a few years ago and had to 'buy' one of those adapters, about $15. If I remember correctly, there were 4-wires (black & whites) and a ground wire with a Big aligator clip. Maybe this will help ya.

 

I hauled a trailer that had to be touching the hitch just right in order for the lights to be grounded. It was usually fine while driving, but the trailer lights wouldn't always come on while just sitting still.

 

for the trailer tow package there are seperate fuses for all of the trailer lights. all under the hood. loc5 20a back up and park, loc 19 10a rh stop turn, loc 20 10a lh stop turn, relay loc 201 park lamp relay, see if those help there are more for trailers with brakes but not needed for a 4 pin. most trucks with the tow package have the installed but not all. see if that helpes.

i put the same reply in elecrtical