Tail lights work but no Turn/Brake

I have a 7 pin plug mounted to a bracket on the bumper. This is wired to a couple of plugs mounted to the frame on the left hand side near the wheel well. These go into a wiring harness that goes all the way up to a big plug under the air filter that has a bunch of other stuff in it as well.

From the plug in the wheel well all the way up to the engine compartment all looks factory.

Since the Tail lights work I know that the ground is good and would assume that the wiring is good. I have tested at the plug in the wheel well and there is no power there on the turn/break pins.

From the big plug under the air filter things start splitting off and going different places. Where should I go from here to troubleshoot?

 

Check the fuse first. See 1997 owner's manual.

 

That was the first thing I did but could not find on for the trailer lights. Found this thread Trailer wiring fuse locations for 1997 f150 4x4 v6 - Ford F150 Forum then went out and sure enough there is another fuse box just aft of the one in the engine compartment with 2 fuses in it. I guess on is Turn/Break and the other is tail.

 

No, read your owner's manual. It's in the 97 manual, page 142....

 

My P142 is Check and Add Washer fluid.

 

fuse and wires on the truck lights are not the same as the trailer lights-- different fuses. Look up year here. Fuse box under the steering column, and also on left fender well.


https://www.fleet.ford.com/maintenan...ls/default.asp

 

Get the latest version of the manual...

 

Check the fuses under the hood.
Also there are relays for the brake/turn lights.
If both sides don't work I'd suspect the fuse first.