2005 Keystone Tailgator 189RR Trailer has Intermittent Brake Light Function on the Left Side  

Question:

Expert Reply:

Since everything else works all the time, we can probably eliminate a bad ground as the source of the problem. If a ground was bad most of the trailer light functions would be intermittent. Since it is just the left brake light, and it works intermittently, the problem is probably on that circuit somewhere. It could be something as simple as a loose connection or a nick in the wire shielding.

We know that the problem is somewhere in between the truck brake light and the left side trailer brake light. To start narrowing down the problem, we need to check the trailer connector on the truck first. Use a circuit tester like part # PTW2993 and check the left brake/turn signal pin on the connector. If it is a 4-Way flat connector, it would be the yellow wire. If you have a 7-Way, it would be the pin in the 9:00 position. Make sure this pin provides brake and blinker signal as it should. I imagine it will be fine and that means the problem is somewhere on the trailer.

Start at the trailer wiring connector. Make sure the wires are securely attached to the connector. Go back to the left blinker/brake light assembly. Check the wires, look for loose or corroded connections. If the lights are stud grounded, you may not have a sufficient connection. Check the studs or bolts and make sure they have good metal contact.

If you still have not found anything to solve the problem, it would be time to trace the wire from the light assembly forward. You could have a nick or scratch somewhere that rubs against the trailer frame and loses the connection. Tracing the wire should not be too difficult it will just take some time. You can bypass the factory wiring and just run a new wire from the connector back to the light.

expert reply by: Patrick B

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