freddyray21
Commander
- Joined
- Jun 10, 2006
- Messages
- 2,460
I see a lot of posts on here about trailer light problems so thought I might post this to make it a bit easier for those having problems. A light functions by voltage, in this case 12v through the filament and then back to a ground. Both voltage and a ground must be present for the light to light. (assuming the bulb is not burned out). The lights on your tow vehicle are not different. By putting in a trailer wiring harness you are just extending the vehicle wiring to the trailer. Most trailer light problems are usually a bad connection somewhere.
If you don't have lights there is a trouble shooting procedure. First check the bulbs that they are not burnt out. Then I check to see if I have power at the connector coming from the vehicle. I will reference everything to a standard four wire system as that is most common. The four wire colors are white (ground), brown (tail light and marker lights), green (right turn and brake) and yellow (left turn and brake). I first check the ground for continuity. Using an ohms meter touch one probe to the white terminal and the other to a good ground on the vehicle. It should read as a closed circuit. My meter has a beep to tell me. If you don't get a beep or closed circuit then the problem lies in the ground most likely. If you do get a beep then using the volt scale on the meter hook the black lead to the white ground terminal. With the vehicle lights on you should have constast 12v's (actually a bit more) to the brown wire. With the right turn signal on you should get a flashing 12v to the green wire. With the left turn signal on you will get a flashing 12 v to the yellow wire. With both turn signals off and the brake pressed you should have 12v constant to both the green and the yellow wires. these are right then the problem lies in the trailer wiring. First check the ground at the trailer. With the lights plugged in testing continuity from the white wire on the trailer side of the connector to a good ground on the vehicle you should get a beep or closed circuit. Most trailer lights themselves at the light are grounded through a white wire running from the light to the frame of the trailer. Make sure you have continuity there and the connections are clean. then do the same voltage tests, but this time at the lights themselves. If you don't have voltage to a wire chances are there is a break in the wire from the connector to the light itself. Trailer wires are exposed to the elements and get brittle and break. Once all your connections are clean and have power there is no reason you should not have lights.
http://www.google.com/imgres?imgurl...OuIngs&sa=X&oi=image_result&resnum=1&ct=image
If you don't have lights there is a trouble shooting procedure. First check the bulbs that they are not burnt out. Then I check to see if I have power at the connector coming from the vehicle. I will reference everything to a standard four wire system as that is most common. The four wire colors are white (ground), brown (tail light and marker lights), green (right turn and brake) and yellow (left turn and brake). I first check the ground for continuity. Using an ohms meter touch one probe to the white terminal and the other to a good ground on the vehicle. It should read as a closed circuit. My meter has a beep to tell me. If you don't get a beep or closed circuit then the problem lies in the ground most likely. If you do get a beep then using the volt scale on the meter hook the black lead to the white ground terminal. With the vehicle lights on you should have constast 12v's (actually a bit more) to the brown wire. With the right turn signal on you should get a flashing 12v to the green wire. With the left turn signal on you will get a flashing 12 v to the yellow wire. With both turn signals off and the brake pressed you should have 12v constant to both the green and the yellow wires. these are right then the problem lies in the trailer wiring. First check the ground at the trailer. With the lights plugged in testing continuity from the white wire on the trailer side of the connector to a good ground on the vehicle you should get a beep or closed circuit. Most trailer lights themselves at the light are grounded through a white wire running from the light to the frame of the trailer. Make sure you have continuity there and the connections are clean. then do the same voltage tests, but this time at the lights themselves. If you don't have voltage to a wire chances are there is a break in the wire from the connector to the light itself. Trailer wires are exposed to the elements and get brittle and break. Once all your connections are clean and have power there is no reason you should not have lights.
http://www.google.com/imgres?imgurl...OuIngs&sa=X&oi=image_result&resnum=1&ct=image