Troubleshooting Curt TriFlex Brake Controller that Flashes 1.0 With No Trailer Connection

Updated 09/22/2025 | Published 11/12/2019

Question:

The display on my C24VV flashes red 1.0 while driving without my trailer on???

asked by: Ed L

Expert Reply:

This is a common issue when there is corrosion built up on the brake output pin of the 7-way. What this does is cause the controller to sense a slight amperage draw which confuses it into thinking a trailer is connected. The other thing you can try is unplugging the controller and plugging it back in. Sometimes the Curt controllers just need to have a hard reset to function normally.

expert reply by: Jameson C

David

9/14/2025

Hi Jameson. I have a somewhat similar but different question for you. I have a CURT TriFlex trailer brake controller (model 51140) which is about ten years old. With my truck turned off, parked in the driveway with no trailer attached, I intermittently get "5.4" output numbers flashing on the controller display (I use an output level of 5.4 when towing my 5th wheel). This flashing seems to randomly happen even though nobody touches the brake pedal or manual override lever. After a while the output numbers flashing turns off and a single dot appears. Eventually, after a period of inactivity, the display goes blank. Then, after a day or more with the display being blank, the whole flashing process repeats itself at random intervals. I just had the truck side 7-pin wiring harness replaced (and it tested fine) but the same flashing problem is still happening, so I'm thinking the issue must be on the truck side. Have you ever seen anything like this? What potential fixes can you suggest? Do I need to call for an exorcist?

Jameson C.

9/15/2025

@David Curt brake controllers are pretty notorious for developing internal bugs over time. Try unplugging the controller for a couple minutes and plugging it back in to see if a hard reset fixes the issue. I suspect it will.

David

9/16/2025

@JamesonC Thanks for the suggestion. Will disconnecting the negative on the truck battery do the same thing as disconnecting the controller wiring harness?

Jameson C.

9/16/2025

@David Depending on how the controller is installed it would do the same thing. If the controller was hardwired to the battery for power and ground it would need to have the controller disconnected.