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Troubleshooting Trailer Lights on a Jayco Camper Flashing All Lights When Running Lights Are On


When u put on running light all lights blink but when u shut off running lights the left directional don’t work


Expert Reply:

It sounds like you have a short in your electrical harness.

You will need a Test Light # PTW2993 to try and determine where the short is located in your harness.

First begin by checking with the connection on your tow vehicle. You want to determine if all your lights blink when your running lights are on. If on a 4-way flat connector the female connector closest to the single male connector is the terminal that powers the running lights of the trailer. The center female connector is for the left turn/brake light and the farthest female connector from the male is for the right turn/brake light.

If the issue is present at the vehicle side connection you may have wires shorting out in your vehicle or a faulty converter module if you have an aftermarket light system. You can check the wiring going into a powered converter to determine if the signal is bad coming into the converter.

If the wiring on the vehicle is fine you will want to verify any adapters that you may be using on your 1990 Jayco. The adapter will need to be tested in the same fashion as the vehicle 4-way to determine if there is an issue with the adapter. You can then continue to test further down the harness until you find an issue. You will need to have any damaged wiring repaired or replaced. If your wiring is beginning to crack it may be time to replace the wiring harness as it is over 30 years old and has been exposed to the elements most of its life.

A harness like the 25 Ft 4-Way Trailer Wiring Harness # A25W2GWB can be used to replace the wiring for just the trailer lighting. If you have the 6-pole square on your vehicle and wish to keep it for charging the battery you can add the 6-Pole Square Trailer Wiring Connector Kit # 37995 to allow you to keep that function.

expert reply by:
Gregory M

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