How to Wire the Stop, Turn and Tail Light, # 30-92-001
Question:
We are trying to fix the clearance and running lights. The clearance lights blink when the left blinker is initiated and the left rear taillight doesnt do anything except blink. Cant tell which wire is ground and some appear to have too much amperage and are melting the contact points. Help?
asked by: Truelove
Expert Reply:
The Stop, Turn and Tail Light, # 30-92-001, has a total of 3 wires. The white wire is the ground and needs to be connected to a clean and corrosion free metal surface. It sounds as if the clearance lights are using the turn signal function instead of the running light function. Usually, the running light function on a trailer is a brown wire. You can use a circuit tester to find the correct wire.
This wire will split off at some point near the rear of the trailer with one end going to the left and one going to the right taillight. This wire can also go to the clearance/marker lights. I have included a video below that explains this. Start at about the 2 minute, 45 second mark. Too many lights on a trailer can cause too much amperage draw on the vehicle system and cause malfunctions. On many clearance lights, there will be two wires. If they are not marked, it may not matter which is ground and which is power. You can use a separate battery to test the wires on the lights to determine which wire does which function.
The taillight sounds as if it is only connected to the turn signal function. It should have one connection to the right turn and brake, usually a yellow wire on trailer wiring (use circuit tester to be sure). The other wire is for running light functions, usually a brown wire. On the # 30-92-001 light, the green wire is for right turn and stop, the white wire is the ground, and the remaining wire is for running lights.
There should only be one wire going to the turn/stop signal connection and one wire going to the taillight connection on each side of the trailer for each light. If the problem persists, check the wiring to/from the vehicle and trailer connectors. If one wire broken or shorted, it can cause many different problems including inaccurate functioning like you have described, or a short could lead to too much power draw. I have included a link to our trailer wiring FAQ for reference.
