Troubleshooting Lack Of Output With A Redarc Tow-Pro Liberty On A 2017 Toyota Highlander

Updated 12/01/2024 | Published 10/30/2024

Question:

I installed the Tekonsha 7-way wiring ITEM 22119 with the Redarc brake controller ITEM RED52VR. 2017 Toyota Highlander Hybrid I dont yet have a trailer to test this, so I tested it with a digital multimeter. Everything checks out, except the blue wire 12V trailer brakes. 1 I tested the brake controller from under the dash across the blue wire 12V trailer brakes and the black wire 12V power. I was getting 12V. Good. I pushed the Redarc brake controller knob in, and I still got 12V. It should have been 0V. Not good. 2 I tested the brake controller across the blue wire and ground and even with the knob engaged, it still red 0V. Is this normal until a trailer is connected?

asked by: Zach S

Expert Reply:

Hi Zach,

Without a trailer connected and the rig moving the only way to get power from to the Liberty # RED52VR to the trailer is to press in the control knob to activate the manual override. When doing this you would see 12 volts coming across the blue output wire running to the vehicle's 7-way.

If you aren't seeing voltage coming across when using the manual override then I would check the blue wire at the harness to see if any output is coming from the brake controller and just not making its way to the 7-way due to some kind of damage or loose connection. If not then there's an issue with the brake controller. If there is then there's a loose connection or short in your wiring that you'll need to fix. Another important thing to check is the ground. If yours is loose or not making good contact with the frame then you'll start to see some oddball issues.

If you still have questions just let me know and I'd be happy to keep troubleshooting with you.

expert reply by: Kevin C

Zach S.

12/1/2024

I solved the issue by using a 22 ohm resistor between the 12V trailer brakes pin and to ground on the 7-pin connection. Everything works great. https://www.redarcelectronics.com/us/resources/brake-controllers-faqs/common-towpro-support-questions/ I went to Redarc's website and they had a FAQ section that detailed how to do this. They specifically call out a 21W, 24V Load Resistor, but I didn't have one. Somewhere I calculated that out to be like 28 ohms, so take that as you will.