Redarc Tow-Pro Liberty Not Showing Solid Blue Light With Trailer Connected  

Question:

Expert Reply:

Hey Jason, thanks for reaching out. Thanks for reaching out. Based on what you're describing, the Tow-Pro Liberty # RED24FR is working normally, but it isn't detecting a trailer. When a trailer is connected and recognized, the LED should change to a solid blue when you're driving. The fact that it only "breathes" blue when you press the manual override tells me the controller has power and the knob is communicating with the main unit, but it isn't seeing an electrical load on the brake output.

Since your tester shows the running lights, turn signals, brake lights, and hazards all working, I'd focus on the trailer brake circuit, not the lighting circuits. Start by checking that the trailer's electric brakes are working and that the blue brake wire has continuity all the way to the brake magnets. Also verify the trailer has a good ground, since a weak or missing ground will prevent the controller from detecting the brake magnets. If you have a multimeter, measure the resistance between the trailer's 7-way brake pin (blue wire) and ground with the trailer unplugged. A typical tandem-axle trailer with four 10" or 12" brake assemblies usually measures around 0.8 to 2 ohms. An open circuit or extremely high resistance points to a broken wire, disconnected magnet, or bad connection. If that checks out, I'd also inspect the blue wire terminal inside both the truck and trailer 7-way connectors for corrosion, a loose terminal, or a pin that's pushed back into the connector housing.

Check all that and let me know your findings.

What kind of trailer are you hauling?

expert reply by: Jesse M

0

Redarc Tow-Pro Liberty Brake Controller - Dash Knob - Up to 2 Axles - Proportional
(click to enlarge)

Jason S.

7/31/2026

Thanks. I think the issue was i hooked up a u hail with hydraulic breaks. Sound like the issue?

Jesse M.

7/31/2026

@JasonS Yea that'll do it. If the trailer isn't detecting an electric brake magnet it will act like no trailer is connected.

Db

8/2/2026

My blue light did not come on until I hooked the trailer up and drove it a few miles to calibrate it. Now it comes on but only when my trailer is connected. 2020 Ridgeline 2026 Jayflight electric brakes.