my trailer wiring is messed up, anyone help?
 

my truck came stock with trailer wiring. when im hooked up to a trailer the right side works no problem. but the left side i get nothing. i checked the voltage starting from the back and i get nothing up to where the wiring goes up into the engine compartment and its pretty hard to follow after that. the fuse is ok. any suggestions? anyone else have this problem?

so this morning i went back out to see whats up and i noticed when i use the right blinker i can hear the relay clicking in the fuse box and it sounds normal (whatever a normal click sounds like). but when i use the left blinker it makes a kinda of boing sound... not sure what this means but to me it sounds like something is broken. i was going to swap the right and left relays to see if the left was faulty. but the relay is inside the fuse box correct? so just the relay cant be canged right?

suggestions anyone?

You should be able to change out the relay or even swap it with the right, as long as they are the same p/n. It sure sounds like a bad relay to me though.

do you know where i can find the relays?

Not sure, don't have my manual here with me but you should be able to locate them by listening to them. Do your 4 ways work ok?

4 ways you mean hazard lights? or blinkers? everything works fine on the truck itself, just the left turn/brake doesnt work on the trailer. i havent tried the hazards yet. ill have to check on that. it sounds like the relays are inside the fuse box. i took the fuse box out and it doesnt look too easy to open up. id hate to break something in there just to find out about a stupid blinker. unless someone has done it and knows how? let me know.

It would seem to me you need to rule out a problem in the trailer wiring before you start chasing stuff on the truck.

You state that without the trailer connected the lights on the truck are fine. This should be a clue. Also that the left flasher is making an unusual sound with the trailer connected. Clue #2.

If it were my setup, I'd take a volt ohm meter and check the trailer connector on the trailer. Since you say the right is working. Start there. Take a resistance measurement on the right side turn signal light by putting one side of the meter in that pin and the other probe on a GOOD ground on the trailer frame. This will give you a reference. I would expect to see a relatively low amount of resistance, on the order of 6-10 ohms. Then do the same on the troublesome left side. I am willing to bet you will see nearly a dead short. (the amount of resistance is determined by Ohm's Law. Voltage divided by current=resistance. so then 12v/2 amps (typical for a turn signal bulb) =6 ohms) Maybe a loose wire in the light housing?

From my experience, when a turn signal flasher is overloaded with too much current draw, it makes an unusual sound as it is actually shutting down like a circuit breaker to protect itself.

the lights on the truck itself work fine with or without the trailer connected. without the trailer hooked up, i checked the voltake at the 4 pin trailer wiring harness on my truck and it reads 12 on the right side and 0 for the left. i kept checking the same wire all the way up to where it enters the engine compartment and it still reads 0. my truck has specific fuses for the left and for the right side trailer lights. when i use the right turn signal, the right relay makes a normal clicking noise. when i use the left turn signal, the relay makes a strange sort of boing noise. i connected the left side of the trailer to the trucks right side turn signal, everything worked great. therefore, i would say there is something wrong with the relay on the truck.

The relays should be the same for the left and the right, swap them around and see if your problem goes to the other side. If it doesn't, then you have another problem, possibly losing voltage somewhere to energize the relay.

thanks AkRam1500. it sounds like the relays are actually inside the fuse box though. im a little hesitant to try and open that up without breaking something else. anyone done this?