How to Adjust a Trailer Brake

In this lesson, we'll review on the adjust a trailer brake on your Service Sanitation vehicle.


When hauling a heavy load, it’s important to make sure your truck and trailer brakes are properly calibrated to keep you and those around you safe.

Getting Started:

To begin, we’ll start by calibrating the trailer brake sensor. This is done by parking the truck on level ground with the connected trailer in tow.  If connected properly, you’ll notice the LED on the front of the module will light up green. This lets you know that you have a complete circuit between the truck and the trailer.

Power Control Knob:

Next we’ll look to the power control knob which is located on the right side of the module to get things dialed in further. As you look to this knob, go ahead and apply the trailer brakes manually by squeezing the brake slider on the front of the unit.  As you do this, you’ll want to simultaneously turn the control knob clockwise toward the front of the vehicle until the maximum setting is reached. The LED light will then turn to a solid red.

You’ve now reached the maximum brake setting and will want to slowly turn the knob counterclockwise towards you, until the LED light changes from red to orange. This should be your ideal sweet spot for transport, but it’s important that you test it before leaving the yard.

Testing the Settings:

To test this, you’ll need to put your truck into drive and let it inch forward at a slow idling speed.  Once in motion, you’ll to perform a few slow stops by using the manual trailer brake slider only.  As you come to a stop, you’ll want to pay attention to see how the trailer performs. If you notice the trailer tires lock up immediately, your setting is too strong.  To correct, you’ll need to turn the control knob counterclockwise towards you ever so slightly and then test again. If the idling truck refuses to stop then you’re settings may not be strong enough. To fix this, you’ll want to turn the control knob clockwise ever so slightly, towards the front of the vehicle and test again.

You’ll know you’re in the sweet spot when the trailer brakes are applied and the idling truck comes to a gradual stop, without the tires locking up.  Once you’ve achieved this, the module should be set and you won’t have to readjust unless the road conditions change or your trailer weight changes significantly.  If at any time your brakes lockup during transport be sure to reduce the settings on the module.

Congratulations, you’ve now successfully set the power output on your trailer brakes to prevent wheel lockups. Good luck and safe travels!