No trailer lights/Brakes

[nhorne]

Installed a P3 controller yesterday, hooked onto a chipper today, and P3 told me no trailer connected. Trailer lights worked, but now they don't. I have checked all the fuses under the dash, and they all appear fine. My test light only shows power to the 12v wire on the plug, nothing else is working. Wondering if there are more fuses, and if there are, where? Also, where does the stock trailer harness ground to? I am at a loss here, and appreciate the help.

-Nate

[88beast]

trailer should be to frame

you have a short always check first

you will not always have power on all leads the brakes only when brake light is on in truck

not much else i can tell you not an expert

[STurbo90]

All the trailer harness fuses are in the underhood distribution fuse box.

Something is not right, installing a new controller should not effect the lights on the trailer, it only sends power to the electic brake actuator wire.

Which plug are you checking and getting 12v?

It almost sounds as if the trailer itself is not grounded, is there an actual wire in the ground spot on the trailer's plug, I have seen lots where the trailer's plug is not grounded to the trailer frame, they just assume it will ground through the ball.

[nhorne]

I have no trailer lights at my 7 pin connector on my truck. I did to start with, now have nothing. My brake controller never did sense brakes, so not sure what to think with that. I'm going to drop the spare to find the ground wire attached to the frame, and see what is going on. I unplugged both connectors under the truck for the trailer harnesses and see nothing wrong (unless I disturbed something). Going to test some stuff out this morning, and see what I can find (its kind of nice to have lights), I would really like to get the brake controller working as well...

[KVOM]

I had lighting problems on my trailer until a mechanic friend showed me a "trick". Some of the contacts on the truck side of the connector had been bent slightly inward so that they didn't make a circuit with the contacts in the plug. He bent them back out very slightly and everything worked. If bent too far out the plug won't go in, so just a little is good.

Don't know if this is the cause of your problem, but if you have voltage at the truck side that's something easy to test.

[nhorne]

Is there any other relays/fuses that aren't under the dash that I may be missing? I have probed the wires before the trailer ground, and all I have is a 12v hot wire, I can't get any other wires to flash, light, etc. Just wondering if there is a relay or fuse I may be missing. The other fuses look good, so I'm at a loss right now. Like to have trailer lights back, as well as trailer brakes, but have no idea why those aren't working. Had lights no brakes, now I have no lights, no brakes...

[STurbo90]

I am not sure if you saw it, but I mentioned above that all the trailer harness fuses are in the underhood distribution fuse box, not the underdash fuse box.

there should also be a relay(2 actually) in a separate receptacle on the side of the distribution box that powers the marker lamps and the 12v keyed for the trailer harness.

Is the trailer the same one you always use? and if so has it always worked fine until you added the P3?

[nhorne]

My fuses are under the dash for turn signals, brake controller, etc. Just wondering if one of the 3 relays by the air filter have anything to do with the trailer harness? When the turn signals are on, I hear them clicking...

[MOUNTAINMAN444]

Yes, check your other post.
Joe

[nhorne]

Joe,

I appreciate the response. Just been scratching my head over this, and haven't been able to determine anything. Going to head to the Ford dealership tomorrow, and see if they can give me an exact answer, and if they have relays...