Troubleshooting Curt Triflex Brake Controller Showing OL Code on Display


Hi, I just installed the curt triflex brake controller and the universal trailer brake 7 way etcb7 on my 2011 Honda Odyssey. I followed your video for install and everything seemed fine until I plugged in my trailer. The code O.L. showed up on the brake controller. I check the trailer wiring and it’s in good shape. I removed and sanded the ground bolt. I checked and changed out the magnets in the trailer brake just in case. I checked the ground wire on vehicle, and it seems fine too. I plugged in a trailer at work and all lights were working but the OL code came on when I pressed brakes. The controller displays braking power when the trailer is not connected, but as soon as I press the brakes with the trailer connected, the OL code appears. Could the brake controller be faulty? And how to test it? Thanks in advance


Expert Reply:

The Curt Triflex brake controller is known to have more problems than other brake controllers so I would not rule out the problem being the controller.

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 am including a link to a video that will show you how to test the wiring on a brake controller.

Let me know what you find and we can continue testing if needed.

expert reply by:
Jameson C

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Follow up Questions

Cody M.

I wired a curt triflex up and it was operating fine before mounting (no trailer plugged in throughout) Once mounted, it started showing OL code. I took it back off the mount and it was fine again. Checked the mount and both screws only touching plastic on the truck. Taking it in for warranty but wanted to share. 94160

Reply from Chris R.

That is really interesting. I've honestly never heard of this issue before (with any brand controller). I assume it was somehow shorting out to the bracket but I'm not sure how..... 69802

Reply from Cody M.

@ChrisR Update, took it to the hitch store and they just replaced the unit. No change to mount and new unit seems fine so far. 69805

Reply from Chris R.

@CodyM That's good news! 70084

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