Troubleshooting Tekonsha Primus IQ TK90160 Showing Voltage Reading When No Trailer Is Connected

Updated 09/07/2021 | Published 09/02/2021

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Question:

Brake controller was hooked up by rv dealership, did initial setting and was on my way. I noticed after about 30 miles that the voltage numbers would rise up to about 3.2 3.4 while accelerating. I got the trailer home and disconnected. Now the controller will rise and fall as I accelerate with out the trailer connected. I’ve tried to reset the controller and still no change. Tried again to reset it, and still showing numbers when not connected, 1.9 in park and still alternating on acceleration.

asked by: Darwin B

Expert Reply:

I reached out to my contact at Tekonsha and based on the issue you are describing it sounds like the RV dealer either used the incorrect plug-and-play wiring adapter, or the functions of your factory trailer brake controller port are mixed up.

The trailer brake controller should not have any voltage shown with no trailer connected as it only sends voltage when it detects resistance on the blue brake output wire.

I recommend using a circuit tester # PTW2993 to test the wires going into the back of the trailer brake controller to confirm their functions.

The blue wire should be open as it only has power when the controller is sending power to the brake assemblies, the white wire is the ground wire, the black wire should have constant 12v power, and the red wire should only have power when the brake pedal is pressed.

I would confirm that the RV dealer used the # 3023-P which plugs into the factory trailer brake controller port, and also have a single connector for the red wire that needs to be connected as well.

If this harness was not used you will need to order it.

If they did use this harness make sure that all of the functions to the trailer brake controller are correct.

Let me know what you find and I would be happy to go into more in-depth troubleshooting if needed.

I included a video of the # 3023-P being installed for you to take a look at.