How to Determine Correct Wiring Connection for Replacement LED Clearance Lights

Question:

I am trying to update my camper clearance lights with LED but its an old camper1978. My question is that the old lights have 4 wires coming out ,how do I connect my 2 wire LED to the 4 wire connection ?looks like 2 run to bulb

asked by: Vance A

Helpful Expert Reply:

Clearance lights function from the running light circuit (that also powers your tail lights) and since this is typically just a 2-wire hookup the extra wires on your lights could simply be there to allow multiple clearance lights to be wired together. Very often in trailer wiring a white wire serves as ground; based on your photo that would make the green wire the + wire for the running light circuit.

You can simply test the light wires on the trailer while you have 12V power connected to the trailer plug. You can use your vehicle battery or a spare and two lengths of wire to make a connection to the trailer's ground and running light contacts; then apply a tester like # PTW2992 to the wire leads for the light to verify that the signal is present. The linked article will show you on which pins on your trailer connector to make the battery power connection.

expert reply by: Adam R