Troubleshooting an E1 Error Code on a Hopkins Agility Trailer Brake Controller

Expert Reply:

It sounds to me like the vehicle side trailer connector is dirty or corroded causing the intermittent functionality of your brake controller. check the vehicle side trailer connector for dirt or corrosion in the connector that may be causing your connection problem. Corrosion can also build up behind the connector where the wires attach. The E1 you are seeing on the controller is an error code for the trailer not being connected.

Next, check is to see if your manual brake override brake lever will work with the trailer connected when the controller is reading the E error code. If the override does work when you are seeing the E, you most likely are having a problem with red stop light switch wire that is coming off of the brake controller. There could also be a blown stop light or CHMSL fuse. Use the owners manual to find their locations on the vehicle.

You would want to check the condition of the connections of that wire at the controller and where it runs to a stop light switch. Next, try severing the blue wire at the back of the brake controller, leaving plenty of wire to reconnect it, and then test all of the wires going into the brake controller and coming out of it. This will tell you if the controller is functioning correctly or not.

Also, be sure the ground on your controller is good. A brake controller should be grounded to the negative battery terminal if it is hardwired to the vehicle.

You can also use a circuit tester like, part # 3808, and have a friend apply the brakes while you test the circuits on your trucks trailer brake pin for the proper signals. If you do not have voltage there you will need to check the wiring, on the back of the plug, for any obvious damage and repair it. If everything checks out you will need to trace the wire all the way back to the brake controller looking for any nicks or breaks on the way.

expert reply by: Michael H