Hello all, i am new to the board. i have a 1997 F-150 supercab with the tow package. the running lights work fine, the right side brake and turn signal works fine, but the left turn signal blinks opposite of the truck(truck blinks>then trailer after truck light is out) and the brake light does not work.. i know the trailor is correct, it works on my brothers f150 and my friends expedition. i DO NOT have an owners manual, so any help you could give me is appreciated. even if you could email me pics of the owners manual that would help.. i know where the fuses are underhood with the relays, but not sure which one's are for what, and dont want to go messing around!!! sorry soo long... thanks.....

 

I had the same problem with mine. It's the number 2 fuse (20 Amp) in the minifuse panel. The minifuse panel is sort of underneath and behind the main engine compartment fuse panel, it's about 1 1/2" x 6". The cover is probably taped on. It seams a little redundant that there are two fuses for the trailer brake light/turns but there are.
Good luck!

 

i checked that fuse, and it wasn't blown, i did try a new 20amp fuse in its place, but it is still doing the same thing! any other suggestions?

 

Main power distribution block -
position #1 = Trailer tow back-up and tail lamps. (20 Amp)
position # 16 = Trailer tow battery charge and stop/turn lamps

 

#1 is a mini and it is fine
#16 is a mega and it too is fine. HELP!!!!!!!!!!!!

 

could this possibly be a relay?
any other idea's of how to track it down?

 

also when the plug is inserted into the receiver, with no power on in the truck, the left brake light on the trailor is on. as soon as you put on the brake, the light goes off and the right brake comes on. THIS SUCKS...

 

I have studied and studied the manual and repair guide aI have and can not find the problem. My mini fuse box under the hood is all relays????? Have you solved the problem yet. I am temp wiring a generic light controller in that I had left from my Jeep. Lots of work but better than a ticket.

 

next to your relay box, there is a small 5inch box on the fenderwell covered in black tape. take off the tape and find 2 mini fuses. fuse 2 could be blown and that might be your problem.... i wish it was mine!!!

 

I have a 97 Expedition, and that box you mention is all relays. There five small relays in the row towards the front of the vehicle and 3 small + 2 large relays in the row toward the firewall. There is one unoccupied slot and one slot with a diode in it.

 

Temporarily connect a wire between the chassis ground and the ground wire for/at the tail light and see if the problem goes away.

The symptom is classic loss of ground.

 

This is definitely a ground problem. You have a poor ground and are getting feedback through the tail lights. Run a separate ground wire as a test and watch the problem go away.

How do I know? Had exactly the same thing... totally corroded tail light mounts on the trailer... new lights... some sand paper to make sure they had complete contact with frame... problem gone.

 

i have run 2 separate grounds and the same problem...the yellow wire is powered all the time, which i know it shouldn't be--which is why i think it is a bad relay sticking open---which is why i need a copy of the owners manual.....

 

Something doesn't add up. If the yellow is powered "all the time", then it should never blink, it should be on steady. Need more info.

The reason that it sounds like ground is the opposite flashing. What it happening is that when the truck signal light is on, there is voltage in both the taillights and signal/brake lights, and no current flows because of the bad ground. When the truck signal light is off, current flows through the tailight wires, then back through the brake/signal wires, causing the light to come on.

If you think you got the ground really correct, ie, you have run a wire from the bulb socket and grounded it to the truck frame, then more information is needed about the yellow wire.

 

the yellow wire when touched with a test light with nothing on in truck(ign.) shows power. hit the brakes and it goes out. put the blinker on, and it blinks after the truck blinks then intermitently stops for a second or two and goes back to blinking opposite the truck again. why would the trailer work on 2 other vehicles if it wasn't grounded properly? or is it the truck's ground which is bad?