Circuit/System Description
The trailer brake control system has a control panel with the trailer gain and manual apply switches. The switches are located on the instrument panel to the left of the steering column. The control panel and switches allow you to adjust the amount of output, referred to as trailer gain, available to the electric trailer brakes and allows you to manually apply the trailer brakes. The trailer brake control panel and switches are used along with the trailer brake display page on the driver information center to adjust and display power output to the trailer brakes.
The internal fault detection is handled inside the trailer brake power control module. No external circuits are involved.
The trailer brake power control module receives inputs from the chassis control module; these inputs are used to determine the amount of voltage supplied to the trailer brakes.
Trailer Brake Controls Description and Operation
A trailer brake control system is used to control the amount of trailer braking power that is made available to trailers with brakes that require a controlled electrical output signal for actuation.
The power output to the trailer brakes is based on both the amount of braking being applied by the vehicle's brake system and on the type of trailer brakes detected.
The Trailer Brake Control System is compatible with two types of Trailer Brake Systems as listed below
- Electric Brakes A controlled electrical output signal energizes an electric-magnet/lever arm assembly that directly actuates the brake mechanism. The GDS name for this system is "Electromagnetic Brakes".
- Electric Over Hydraulic Brakes A controlled electrical output signal energizes a remote, trailer mounted hydraulic pump to build brake pressure in a closed hydraulic system on the trailer. The hydraulic fluid pressure actuates the brake mechanism. The GDS name for this system is "Electrohydraulic Brakes".
Trailer Brake Output Versus Trailer Brake Type
- The trailer brake system determines the trailer brake type (Electric Brake or Electric Over Hydraulic Brake) automatically.
- The trailer brake output may be different based on the trailer brake type determination. An example of this is at zero speed, pressing the service brake pedal will produce output for Electric Brakes, but not for Electric Over Hydraulic Brakes.
- Sliding the manual trailer brake apply lever will produce output at zero speed for both types.
The user gain allows the driver to adjust the amount of trailer brake output to match the trailer load and road surface. The controller determines the desired trailer brake output and provides a control signal to the K133 Trailer Brake Power Control Module. The K133 Trailer Brake Power Control Module amplifies the signal and provides the output required to activate the Electric or Electric Over Hydraulic trailer brakes.
The trailer brake control can support up to a maximum of four axles with electric trailer brakes (8 brake magnets).
Connecting a trailer that is not compatible with the trailer brake system may result in reduced or complete loss of trailer braking. There may be an increase in stopping distance or trailer instability which could result in personal injury or damage to the vehicle, trailer or other property. An aftermarket controller may be available for use with trailers with surge or air trailer brake systems.
To determine the type of brakes on your trailer and the availability of controllers, check with your trailer manufacturer or dealer. Do not power up an aftermarket controller with the factory brake controller at the same time.
The vehicle is equipped with the following trailer braking components
- K38 Chassis Control Module
- K133 Trailer Brake Power Control Module
- S76 Trailer Brake Control Panel
- Manual Trailer Brake Apply
- Trailer Gain Adjustment
- Trailer Brake Driver Information Center Display