Troubleshooting Trailer Wiring Harness # C56217 on 2011 Toyota Highlander

Question:

Installed it and it doesnt work. Installed the inline fuse, which was not already installed. Also, you show the 10 amp under the hood in a different spot than the fuse box diagram 2nd to last instead of last. Tried both spots, still doesnt work. Any ideas?

asked by: Scott

Expert Reply:

As a first step, run through the installation instructions again and verify the installation procedure. Ensure that the converter is securely plugged into the connector under the dash. Give the converter a gentle tug to ensure the plug is securely seated into the connector. Do the same with the trailer connector at the rear of the vehicle.

Once this is verified, you will need to use a circuit tester like part # PTW2993 on the trailer connector. Test the pin socket fed by the brown wire while the vehicle headlights are on. Test the socket fed by the green wire while activating the right turn signal and applying the brake pedal. Test the socket fed by the yellow wire while the left turn signal is activated, and the brake pedal is pushed.

If you are getting no signal at the trailer connector, then troubleshoot the converter box plugged in under the dash. The box has an INPUT side and an OUTPUT side. Use the tester to check each wire on the INPUT side as its function (brake, L and R turn signal, running lights) is activated. Test the circuits on the OUTPUT side while each function is activated. If you have no power entering the converter on the input side of the box, it would indicate a problem with the vehicle itself that would need to be addressed by your Toyota Dealer. If there is power entering but not leaving the box, it would indicate that the box itself is faulty, and would need replacing. If there is power entering and leaving the converter, there might be a disruption or break in the wiring between the front and the rear of the vehicle. You can confirm this by unplugging the trailer connector from the plug at the rear of the vehicle and testing the connector it plugs into while the various lighting functions are activated. If you get no signal at this connector, it confirms that there is a disruption in the wiring that the dealer would need to repair. If you do get a signal on that connector, the rear trailer connector portion of the # C56217 is faulty.

My contact in Tech Services at Curt Manufacturing confirms that the fuse should be inserted in position # 30.

Please run through the items mentioned above and let me know what you find.

I have linked you to a troubleshooting video that you might find helpful.