right turn and stop light don't work on boat trailer from 95 explorer

 

Time to start troubleshooting! Do you have a Volt Meter or Digital MultiMeter (DMM)? Is this the first time the trailor has been connected, or is this a recent failure? Have you already replaced the bulbs?

 

Do you have a ground run throught the connector? I would....... Don't rely on the ball for the ground.

 

replaced all bulbs, checked all grounds, have 1 white wire on trailer that i attached to trailer tongue as ground. do i need to run seperate ground to vehicle? also heard that if vehicle has seperate yellow turn signals need special adaptor. 95 explorer in question has factory trailer plug under rear bumper.

 

all bulbs work/replaced, both turn/signal lamps new. trailer has 8 running lights. heard if vehicle has seperate yellow turn signals need special adaptor. Why doesn't factory harness connect to yellow signals if so?

 

What kind of connectors do you have on the car and trailer (4-pin flat, 6-pin round, 7-pin round)? Are both the car and trailer the same?

If both are the flat 4-pin, and the 4-pin connector on Explorer is factory, it should work. If it is not factory, you might need the signal converter. I am not sure if the '95 needs this or not.

 

YES, you do need to run a seperate ground. Cheap and dirty and all works better after that.

 

First things first, have you checked the terminals using a meter on the truck plug as alluded to by LV DAN. If you don't have a meter, you can use a small 12V bulb and 2 wires (note: dont use a headlamp, it will pull too many amps). If you have the 4 terminal flat plug it should have 1 male end and 3 female ends on the truck side. The 1 male end is the ground. The other three are tail lights, right turn/stop, and left turn/stop. Check for power between the ground terminal and the other 3 one at a time. One way to do this with one person is to turn on the park lights and the 4 way flashers. Obviously with the 4 ways the power will be cycling on and off for both the right and left trun/stop lights. If that all checks out OK, then the problem is on the trailer end. I suspect your truck ground is OK based on the fact that only the right turn/stop light dosen't work. However, on the trailer side, grounding through the frame is not great. If the problem is confirmed on the trailer end, I'd suggest running a ground wire from the white wire on the plug to the light grounds on both sides, but still keep it grounded to the frame as well.

 

As an alternative to a meter or bulb, I bought a trailer plug that has LEDs in it that you can plug into the car's trailer plug. If the car end is correct, the lights work like the trailer's would. It only cost $8.