Brake Lights and Turn Signals Are Not Working on Utility Trailer

Expert Reply:

When trailer lights are malfunctioning, there are many possible causes. As a first step, you will want to use a circuit tester such as part # 40376 and test the trailer connector on your Grand Cherokee. This will help you determine if the problem exists with the trailer or with the vehicle. Test each pin as its function is activated. If you are not getting current at the right or left turn/brake light pins, you will want to check the tow package fuses if your Grand Cherokee was equipped with the factory tow package.

If you do not have the tow package, trace the wires back from the trailer connector, until you locate the converter. This will be a small black box. With a helper on hand to activate the turn and brake light signals, use the tester to check for signal entering and leaving the box. If you are getting power entering the box but not leaving it, the converter is bad and must be replaced. We offer a replacement, part # 118348.

If the trailer connector checked out all right, start at the connector on the trailer. Examine it for damage or corrosion. Make sure that the ground wire is securely attached to metal on the trailer frame, and that this connection point is not corroded. Trace each circuit back to the fixture, looking for broken or pinched wires, or wires with worn or cracked insulation.

The chances are excellent that one of these issues is causing your problem.

expert reply by: Mike L