Trailer wiring troubleshoot
All lights work now except for the right rear park/brake/signal light. There’s about 10 leds, 4 in the middle are the park lights and the remaining are for signal/brake. Rear housing shows wiring diagram (smart). However, the 4 center ones only light up very weak, and with brake/signal applied they do stay one/blink but very weak. So I took off the light and unharnessed the wire (red) for the brake/signal. The feed wire (green) is reading full voltage. I then put the two wires together directly, still not working right.
So I’m thinking it might be the led signal itself. Would it be common for one of those to go?
Followup #1
I traced that green wire to under the trailer and discovered a spot where insulation was rubbed out (mid section of trailer). It was bound tight with a zip tie, so a bit surprised to see the rubbed area.
So I spliced that out and put in a piece to bridge the gap.
Still no luck. From this point the green wire runs right to the plug in the bumper, green wire on the right.
That 5 wire (4 pin) plug plugs into the Reese Towpower plug adapter. So far as I can figure:
- The white wire is ground.
- The black and yellow/black wires are park lights.
- The Yellow is left signal/stop.
- The green is right signal/stop.
The female ends on the Reese adapter reads good voltage. So up to that point there’s power going to the wires.
The only thing I have not done yet is do a resistence reading from that green male pin to the green wire at the taillight.
So far as I know at this point the green wire runs from the plug to the rear right light and controls the right brake/signal function. I’m thinking the best thing to do is simply replace the entire length of green wire.
Followup #2
Last night I took a spare plug, the plug (see below) and inserted it into the Reese adapter. I then ran a wire directly to the right rear light. The resistence check was ok. With the signal on, the signal flashed but only the middle four LEDs and very weak. I sort of suspected a fault because all I was doing was running power to the light, with no ground or other wires hooked up. At least it flashed.
Next thing I tried was cut the trailer’s green wire and alligator clipped a 25′ length of wire from the green wire leading from that male plug (below) all the way to the red wire on the right rear light. Then plugged it into the Reese adapter. Turned on the right signal. Nothing. Scratching my head at this point.
Well this is what I get for F’n around with something to save money, then turn around and do this. Don’t ask how I did it. Its done. And now its going to cost me $3,000 or so to fix it. Unless of course I get the idea to try and fix it myself and end up burning down the garage or something stupid like that.
But if you’re curious as to what happened, I had to move the truck to make way for family arriving for Thanksgiving. I went to the back of the truck, seen the wire unplugged, figured “Good to go.” I pulled up the driveway and put it into reverse to park on the other side of the garage. I didn’t stop until I bought up solid…the trailer was still hitched and I didn’t see/feel it as I moved. :(:(:(
8 Comments
Mike
Remove your left light and try on the right side to see if that works. If it does work then you have a light issue, if it doesn’t then it’s a wiring issue. Start with that.
Jim Barry
I swapped out the lights and the right side still does not work. Notes are above.
Gerald Wall
Not common for one of those lights to fail but it has happened. I’ll check on it and be back to you later.
Gerald
Jim Barry
Hi Gerald, Thanks for looking into this. That light lens actual had water in it, about 1/2 inch, I had to drill a small hole in the bottom it drain it but it did not affect performance because when I swapped it to the other side the light worked.
Bryan Cowing
I would guess a corroded connection or a rub through that has corroded and won’t pass the whole 12v. Check all splices, even the first one after the trailer plug. Electrical tape is good at holding water.
Jim Barry
I did find a rubbed piece, see above. There’s no electrical tape used in the wiring, new trailer bought in 2011 bought from linklettermfg.com, local manufacturer.
kysor1211
Sounds like a ground issue…. make sure the light is grounded good.
Jim Barry
Grounds are good.