Troubleshooting "Short" Error Message On Curt TriFlex NEXT C24VV

Updated 11/17/2025 | Published 09/26/2024

Question:

I just replaced the old brake controller on my GMC C3500 with a Curt Triflex Next. The controller is working to control the brakes while I am towing my trailer. When I squeeze the manual trigger without my trailer connected it simply gives me the Disconnectedinch status on the display. If I squeeze it with the trailer connected it does operate the brakes, but displays Shortinch on the screen. The trailer was just returned from having the brakes redone at the shop and all work fine with their controller different brand. None of the bulbs are out. What would be the best way to trouble shoot this? Thank you.

asked by: Kevin

Expert Reply:

Hello Kevin, thanks for reaching out. It sounds like you have already done the most helpful troubleshooting step by hooking up another controller and verifying that everything works fine. This eliminates the trailer wiring as a potential cause of the issue and it also eliminates the truck as a culprit as well. That really leaves us with the controller as the cause of the issue, more specifically an internal short. You can try cutting the blue wire coming from the controller at least 6" back. If the code goes away this means the wire coming from the 7-way connector has a short and needs to be fixed. If the code does not go away there is an internal short and you will need to replace the controller under warranty. If you purchased the controller from us, just give customer service a call with your order number and they can get the ball rolling on that.

expert reply by: Jesse M

Lowell

11/11/2025

Jesse, The original poster's issue is exactly what I'm experiencing with my 06 GMC 2500HD and recent install of a Curt TriFlex i bought from etrailer. Was there any followup from the OP? I'm currently in an email conversation with a Curt rep about troubleshooting steps. The Curt rep told me to cut the red wire to check things, but I need more clarity before I cut into the harness on my new brake controller. Thanks, Lowell

Jesse M.

11/12/2025

@Lowell Doesn't look like we ever heard back from the OP here. Cutting the blue wire is the standard test we recommend. Go ahead and cut it about 6" back from the controller and see if the error code clears.

Lowell

11/12/2025

@JesseM Thanks for the reply. I did the blue wire cut this morning. Got a "disconnected" message on the controller. Pressing the manual switch did not result in a "short" message. So that implies an issue with the trailer wiring. All the lamps back there illuminate - running/turn/brake. There are two pins on the trailer side of the 7 way that show a route to ground. The ground pin shows resistance of about 0.1 ohms using my multimeter. The brake pin shows about 1.2 ohms of resistance. Some research I did indicates that the resistance through each of the brake magnets should be about 3.5 ohms. I've got 4 brakes, so paralleled, one should see just under 1 ohm when checking at the trailer connector. So my 1.2 ohms is in the ball park when factoring the length of the wiring run and various wiring connections. Since it appears the TriFlex is looking at the resistance of the brake circuit, could the threshold of detection in the controller be set too low? Is there a way to change that? I'm somewhat confused about the troubleshooting steps in the little manual on page 14 and the description of the conditions that can set the short message on page 10. Just had a thought --- I have higher intensity LED brake lights on the back of the truck. Could the controller somehow be detecting that through the brake switch circuit? Thanks for the help. Lowell

Jesse M.

11/12/2025

@Lowell Yes I agree this does sound like a problem with the trailer wiring. Start by checking the 7-way trailer connector for corrosion, bent pins, or exposed wires. Next, trace the blue brake wire along the trailer frame for any cuts, pinches, or rubbed spots. Inspect connections inside the junction box and at the brake magnets for loose or frayed wires. The ohm reading for your brakes sounds normal. What kind of trailer is this?