Troubleshooting Curt Discovery Brake Controller That Stopped Working on Third Trip

Updated 06/25/2025 | Published 10/24/2019

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Question:

I found the issue was a faulty 3 port connector where the wires connect the power and the 2 brake wires right before they enter the back of the drum. There was a bad connection inside the connector. I replaced the connector and wired it and everything works fine now. Thanks for the help.

asked by: Chancy B

Helpful Expert Reply:

Some of the Curt brake controllers are known to have internal issues which it sounds like you are experiencing as well. Since you tried resetting the controller by unplugging and plugging back in most likely it is an internal issue but we can help diagnose this.

Testing the brake controller is fairly easy. Sever the blue brake output wire near the brake controller leaving enough room to reconnect it and then apply the manual slide. Using a circuit tester like the Quickee Tester, part # PTW2993, you should get output to the controller side of the wire you severed. If the manual slide activates the trailer brake output wire properly, try the brake pedal. If the brake pedal activates the brake output properly also then the problem is farther back either in the vehicle wiring or on the trailer.

If either the brake pedal or the manual slide are not functioning properly you will need to test the wires going into the brake controller. Make sure you have power entering the brake controller on the black wire. On the red wire you will only want power when the brake pedal is pressed.

If there is power on the red wire before the brake pedal is pressed you have connected the red wire from the brake controller to the wrong circuit. You would then need to find the brake switch wire that has power ONLY when the brake pedal is activated.

If these connections check out and the brake controller is properly grounded then there is possibly a problem inside the brake controller. I attached a video link on brake controller troubleshooting as well. This controller has a limited lifetime warranty as well which means that if the testing does come back as it being the problem you should contact who you bought it from and see about getting it replaced.

expert reply by: Jameson C

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Chancy B.

9/30/2019

Thanks for the help! So, I disconnected the blue wire from the brake controller and I have constant 12v DC power coming out of the controller. The truck is not turned on and the brake pedal is not pressed and the manual slide is not pushed in. I should only have power on the blue wire coming from the brake controller when the brake pedal is pressed and/or when the manual slide is pushed in correct?

Jameson C.

9/30/2019

You are correct. The blue wire should only have power if the brake pedal is pressed or if the manual override lever is slid. Since yours has power all the time the controller is shot and would need to be replaced. It has a limited lifetime warranty so you'd want to contact who you bought it from and they should set you up with a replacement.

Chancy B.

10/24/2019

Jameson C.

10/24/2019

Glad you got it fixed and thanks for passing on what the solution was! I am posting this on our site so that it might help someone else in your situation.

Jerome O.

6/14/2025

Hello! I am trying to figure out why brake on trailer not working. I have Curt Spectrum brake control. Company installed it about 5 yrs ago. All brake lights work on both truck and trailer. I see only 1 red light on the control when I press on brake. I tried adjusting the controller but still can’t get brake from trailer. What could be the problems ?

Jameson C.

6/16/2025

@JeromeO Have you tried cleaning the pins of your 7-way? Typically this issue is just a matter of the controller not sensing a trailer connection due to corrosion or dirt on the 7-way. Sandpaper usually does the trick.

Jerome O.

6/16/2025

@JamesonC Hi I’m not sure what you mean by clean the pin of 7 way?

Jameson C.

6/16/2025

@JeromeO The metal pins/contacts in the 7-way trailer wiring connectors. They pretty commonly get covered in corrosion which prevents the contact from being made.