Trailer Brakes Not Working When Moving Activator II from a 2000 to a 2008 Toyota Tundra

Expert Reply:

Since you have the factory 7-Way and brake controller wiring, I would imagine everything is correct on the truck. Additionally, using the custom fit brake control harness, part # 20265, eliminates concern of the brake controller being wired incorrectly unless the harness is faulty which is very unlikely. I would use the instructions for 20265 to make sure that the pins are in the proper location. I have linked to these instructions below.

The single decimal point, as you may already know, indicates that the brake controller is active and is receiving power but there is no trailer connected or the brake circuit is not complete. This can be caused by incorrect wiring of the brake controller which is probably not your case since you used the 20265. It can also be caused by the brake magnet wires on the trailer fraying or disconnecting. You can check these wires behind the brake assembly. Make sure one of the wires from each magnet is securely connected to the brake wire running from the connector and that the other is securely grounded to the trailer frame or axle.

A bad ground connection between the trailer and the vehicle can also cause this problem. It can also cause intermittent malfunctions of the trailer lights. Check the contacts on the trailer connector and make sure they are free of corrosion and debris. Check the ground wires on the connectors, both truck and trailer, and make sure they have good metal contact to the truck frame and trailer frame.

Please write back and let me know what you find and how you make out and we can go from there.

expert reply by: Patrick B