How to How Trailer Taillights Get Wired Up

Question:

I wired white to frame as a ground black to running lights and red to turn signals and break but now both sides flash with right or left turn signals? What am I doing wrong?

asked by: Zachary

Expert Reply:

Trailer wiring colors can vary from trailer to trailer so it's not a reliable way to wire up a trailer.

You will want to first determine which wire of each taillight signal carries the brighter and dimmer circuits. The dimmer of the two will be for the running lights and the brighter will be for the stop/turn circuit.

Next, you will want to use a circuit tester like part # PTW2993 to test all of the wires on the trailer as it is connected to a tow vehicle and all of the taillight circuits are applied. This will help you determine which wire does what and how it should be wired to you trailer.

expert reply by: Jameson C

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Jack C.

3/17/2020

I need both passenger and drivers side. does it matter what side I order?

Chris R.

3/18/2020

The only difference between the driver and passenger side assemblies is that the Driver's Side # STL9RB features a license plate light. So if you plan on mounting the trailer's plate beneath the light you'll want to make sure you order accordingly. The passenger side assembly is part # STL8RB.

Helpful Links

Trailer-Lights/Optronics/STL8RB.html

Trailer-Lights/Optronics/STL9RB.html