Troubleshooting a Tekonsha Primus Brake Controller Displaying 0.0 and Not Braking

Updated 02/10/2020 | Published 10/18/2011

Question:

I recently changed my trailer lights to LEDs, blew a few fuses in doing so. Now my Primus brake controller shows 0.0 volts when I apply brakes. Did I blow a larger fuse Im not aware of? 2004 chevy trailblazer

asked by: Richard

Expert Reply:

It sounds like there might be some other fuses that could have blown, or there are some shorts on your brake controller/7-way circuits.

It is hard to know exactly where the problem lies, but the first thing I would check would be to test the manual override lever when the trailer is connected and see if it will apply the trailer brakes. If it does have voltage then I would check to make sure brake switch circuit (red wire) sees voltage when the brakes are applied. If not, then you have located the problem and will need to inspect this wire for loose wires or corrosion and fix as necessary.

The next thing to test will be the brake output circuit (blue wire) from the brake controller. The easiest way to test this will be to cut the wire and then test for voltage on the side from the brake controller with the manual lever applied. If you get voltage here then you know that the problem lies somewhere in the wiring between the brake controller and the 7-way trailer connector. At this point you will want to start by testing the trailer connector for voltage on the brake output circuit of your 7-way, this should be the blade in the 5:00 position. At this point you will need to work from there back to the front of your vehicle on this circuit checking for voltage until you find it. Once you have found voltage you will have narrowed down where the problem is. You will need to look for any loose or exposed wire and corrosion and fix as necessary.

You might also try setting up your brake controller again just to make sure something is not just out of adjustment. I attached installation instructions for this product for you to check out also.

expert reply by: Jameson C

Ray

2/7/2020

Have all trailer lights ,brake turn and run , but have no power to the controller , therefore I have no brakes . The controller is working as we put it into another truck. Im thinking the problem is in the truck might be a fuse. Question is which on I look in the manual and it dont seem to be much help. 2011 F150 . Last time I pulled the trailer the brakes worked fine.

Jason S.

2/10/2020

For your Tekonsha Primus Brake Controller # TK90160 since you have confirmed the power issue is not with the controller itself, you will want to check your fuse on your 2011 F-150 as you mentioned. The fuse you will need to check is in the engine bay fuse box, #21 which is a 30 amp fuse. You will also want to check fuse #37 which is a 10 amp fuse. Also #17 which is a 30 amp fuse. You can find the locations using your owners manual.