No Left Turn or Left Brake on Rewired Trailer When Connected To 7-Way on 2013 Porsche Cayenne  

Question:

Expert Reply:

You can test the 7-Way connectors on the Porsche Cayenne or Mercedes ML250 and the trailer with a circuit tester, part # PTW2993. I am including a link to a FAQ page on trailer wiring that will show you the functions of each pin on your connector, depending on if it is either a 4-Way, 5-Way, 6-Way, or 7-Way. This will help you determine if there is a problem with the wiring on the vehicle or the trailer.

If you are using the Pollak 7 Round to 4 Flat Wiring Adapter, part # PK12742, you will also want to test your functions with the adapter connected to the 7-Way to make sure there are no problems with the adapter.

Also, I would recommend to test the ground connections on the vehicle and the trailer. When you find that some of the lighting functions work, but not all of them it is always best to check the ground connections.

I would check the ground on the connector on the Cayenne or ML250 to make sure it is attached to a good, clean ground on the vehicle frame.

Also, check the ground on the trailer connector which should be attached to a good, clean ground on the frame of the trailer.

The last thing to check is the tail light assemblies on the trailer to make sure they are grounded. Trailer tail lights can be grounded in one of two ways. The first way is the tail light assemblies can be grounded by a separate wire coming out of the back of the tail light and attached to the trailers frame. The second way is the tail lamp assembly is grounded through the mounting bolt that attaches the tail light to the frame.

If after trying the above procedures you still are having problems please let me know so we can pursue other options to help you solve the problem.

expert reply by: Jeff D

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