Setting Up a Tekonsha Primus Trailer Brake Controller without a Boost Feature

Updated 03/28/2025 | Published 09/17/2011

Question:

This model of Tekonsha PRIMUS IQ brake controller doesnt have a boost button, but it does have a blue lever on the right hand side. What is the lever for and is it used in calibrationg the unit?

asked by: Max K

Expert Reply:

The newer Tekonsha PRIMUS IQ, # TK90160, does have a boost button on top of the unit above the display. Earlier versions like yours came without a boost button. For either style, the lever that is on the bottom of the brake controller is the manual override which allows you to manual engage the trailer brakes without stepping on the brake pedal.

When setting up the controller, you will use the manual override lever. First, you connect the trailer to the towing vehicle and start the engine. Then hold the manual override fully in the left position and while holding it there, set the power knob to 6.0.

You will then drive on a flat surface at 25 miles per hour and then fully engage the manual override. If the trailer brakes lock up you will adjust the power down. If braking is not sufficient you will adjust the power higher. You want to get it to a point just under trailer brake lock up. After you have it set, test it out using the brake pedal and adjust as needed.

expert reply by: Michael H

Ryan

3/28/2025

He is talking about the reaction time lever, not the manual brake activator.. this blue lever tells the brakes how fast to react, one side of the swing being almost immediate activation of the brakes while the other side of the swing is a slow activation, not as violent.