Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Module, Integrated Trailer Brake (ITBM): Operation
The Integrated Trailer Brake Module (ITBM) controls the electric braking and the Electric Over Hydraulic (EOH) braking for the trailers that are properly connected to the vehicle. The ITBM controls the electric brakes of a trailer in order to reduce the braking distance and a better dynamic behavior of the vehicle trailer system and includes data for Electronic Stability Program (ESP), Hill Start Assist (HSA), Active Cruise Control (ACC) and Forward Collision Warning (FCW) as well as trailer sway events.
The ITBM receives odometer data from the Instrument Panel Cluster (IPC) over the Controller Area Network - Chassis (CAN-C) data bus from which the ITBM calculates the mileage distance for the trailer that has been connected to the vehicle. The mileage accumulates across key cycles for as long as the trailer is connected to the vehicle. This calculation is then sent to the IPC over the CAN-C data bus to be used in displaying the trailer trip information to the driver or reset using the Electronic Vehicle Information Center (EVIC) switch for the trailer trip odometer.
The trailer trip odometer feature will only work with trailers that are equipped with electric or EOH brakes and the trailer must be connected to the vehicle. A diagnostic scan tool must show an electric trailer detected.
Automatic Braking - Based on Integrated Trailer Brake Switch (ITBS) inputs from the vehicle operator, the ITBM is capable of:
- Adjusting the gain depending what the vehicle operator inputs on the ITBS
- Controlling the trailer brakes - electrical or EOH
- Calculating the output signals
- Diagnosis the elements involved and communicate information to the vehicle network
- Applying the brakes depending on the status of the ITBS manual lever
- Communicating the status of the braking and trailer to the IPC
- Being selectable between electric brakes and EOH brakes
- Adjusting the aggressiveness based on what type of trailer brake system is selected in the IPC
- Reacting to preemptive trailer sway events and during a trailer sway event to improve the control and braking of the vehicle
- Reacting during an HSA event to minimize the rollback feeling
- Helping to avoid the noise on the hitch during a stop and go
The ITBM monitors the CAN-C bus network for data broadcast by other modules on the CAN-C bus. The ITBM is responsible for its own logic, actuation and sensing.
Hardwired circuits to and from the ITBM include the following:
- B+ power supply from the Power Distribution Center (PDC)
- Fused RUN/START relay output from the PDC
- Trailer brake gain data
- Manual trailer brake input
- Trailer present test signal to ITBS
- Trailer present from ITBS
- Brake signal from the Antilock Brake System (ABS) module
- Pulse Width Modulating (PWM) electric brake feed to the trailer connector
CAN-C inputs received by the ITBM include the following:
- Vehicle configuration data
- ESP brake data from the ABS module
- Driver Assist System Module (DASM) data
- Engine fuel type
- IPC odometer
CAN-C outputs sent by the ITBM include the following:
- IPC display requests
- Trailer brake status - check pass or fail
- Trailer brake control output signal to the trailer based on the brake pressure in the master cylinder and also based on the type of trailer and gain input from the user
- Trailer connection status and information signal
- Chime requests
- Trailer configuration data
- Trailer brake style
- Trailer brake PWM feed output value
- Trailer brake warning status
- Display request
- Trailer status
- Trailer odometer calculation to IPC
Body Control Module (BCM) inputs and outputs include:
CAN-C inputs:
- Trailer configuration data
- Trailer status
CAN-C outputs:
- Ignition status
- Battery voltage
CAN-IHS outputs:
- Trailer configuration data
- Trailer status
Manual Trailer Braking - In addition to automatic trailer braking, the user can manually apply the trailer brakes prior to or without the vehicle brakes by sliding the ITBS manual sliding brake lever to the left at any time.
The ITBS is located on the left side of the switch bank pod. The ITBS is comprised of a +/- gain adjustment switch (1) and a manual sliding trailer brake apply lever below the gain adjustment switch. The ITBS is hardwired to the ITBM.
The switch bank pod and the ITBS are separately serviceable components, however, the ITBS can only be serviced by removing the switch bank pod. Refer to POD, SWITCH, REMOVAL .
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.