Troubleshooting Tekonsha Primus Brake Controller that Lights Up Truck Third Brake Light

Question:

I purchased a 2012 Dodge Ram 1500 5.7 hemi that has this unit installed on it. The problem I am having is it keeps my 3rd Brake Light on. It not only drain my battery but my trailer brakes be ingaged and I cannot pull my travel trailer that I recently acquired.

asked by: Lisa J

Expert Reply:

What's happening is that the Tekonsha Primus IQ part # TK90160 is backfeeding 12 volts to the stoplight circuit (red wire) which it is not supposed to be doing. This circuit on the controller should not be active all the time so this happening would be evidence that something is wrong with the controller. Most likely an internal short that isn't fixable. You might try unplugging the controller and then plugging it back in and see if a hard reset clears up the short. If not, it would be time to replace the controller.

For a replacement I would recommend the better performing and more reliable P2 part # 90885 which is the next generation of the Primus. It has a more advanced inertia sensor and even uses the same connector so you can easily just plug it in.

expert reply by: Jameson C