2000 F150 with tow package: Basic problem: lights are very dim; I have 2 - 4” round tail/stop & turn lights on each side of my enclosed trailer and several clearance lights front & rear; everything used to work fine. When I disconnect one tail/stop & turn light on each side, the rest get bright enough to see other problems: all lights flash when using turn signals and taillights; in fact, when stalk is in the left turn position in truck, the right turn signal is brighter on trailer and visa versa. BTW, I hooked the truck up to a small trailer I have (fewer lights), and it works fine.
I've searched the forums and been from one end to the other of the trailer trying to fix this problem. I've installed new wires to the lights with quality connectors where I couldn't solder the connections. I've checked every ground and light on the trailer. Now I’m wondering if a connection in the truck is causing the problem? I found a connection from the truck’s trailer connector wiring to the left taillight wiring; it has 5 small pins that were corroded, and I cleaned them. I noticed the Pollak trailer connector on the truck has a connection going into the back of it, but can’t get it apart. HELP!
Thanks in advance,

Dan

 

I fergot sumptin when I enclosed the trailer. The rear door swings down as a ramp. The taillights are in the rear door. The "ground" all this time has been the hinges, which have now rusted. If I towed it a few miles it'd probably "fix itself". Not gonna happen. I'll post after I properly ground the door tomorrow...

 

Sounds right....
I was thinking ground while reading the whole 1st post.

 

I already had a ground wire running into the door. Installed a strap from the door to the frame anyway, no difference.
I left one light in each side out (disconnected & wrapped it up, put it back in hole). The only problem now is the turn signals bleed into the running lights, but the correct one lights up when it's needed. While not perfect, that's the way it's going to be for this trip. When 4" round LEDs come down in price I'll put them in, as I'm wondering if I just have too much power draw with 4 stop & tails.
Obviously, I'm still looking for ideas...
THANKS,

Dan

 

You still have a bad connection. Use a voltmeter and measure for voltage drop across what should be a continuous circuit.

Steve

 

Check each light's ground to frame/door connection. Either and at the light fixture itself if self grounding or the ground wire from the light fixture if it has one.
It sounds like the light is working fine and getting power then backfeeding up the other line instead of out the ground.

 

definately a ground problem! remove your taillight housings and attach a ground wire from each housing directly to the trailer frame if you can. I had the same problem on a camper. The lights were grounded to the aluminum shell of the trailer. Aluminum is not the greatest conductor, so any corrosion at the grounding points (even if they look good)makes it even worse.

 

I'm not an electrician; won't there be a voltage drop across each bulb?
The idea of the pigtail itself having an internal ground problem is interesting. The pigtails are a bit warped, apparently from heat. Can I check this with everything hooked up?
The taillights are plastic and contain tail, stop & turn and grounding wires (in separate pigtail, which connects to the light).
I'm checking on LED lights and new pigtails, but they're not local, so it'll be a while...

Still

 

not one you'll likely run across. Working on things like this should be punishment for polititians caught with their hand in the cookie jar. The front of the trailer had a negative ground and the rear had a positive ground. You heard me. I was ready to rewire again because I could swear the wires were screwed up.
This was a flatbed trailer I enclosed. As a flatbed, it was made to pivot in the center, bringing the back of the trailer to ground level so I didn't have to lift ramps to load the car (bad back). It has a floor jack welded into the frame up front that you use to tilt the trailer. I still use that function. Now, why did I have the problems I did? I'm going to let you figure it out. Hint: similar to what I thought the problem was in my second post.

Time for a little ...

Dan