Theory Of Operation

WARNING: This page is about a different car, the 2017 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.

The Integrated Trailer Brake Module (ITBM) communicates with the vehicle through the high speed CAN C bus. The ITBM monitors the Brake Pedal Status, Vehicle Speed and ESP status via CAN message. It also displays outputs of the Trailer Status, Gain Setting, Trailer Brake Output Power to the vehicle and message errors through the Electronic Vehicle Information Center (EVIC) in the cluster. The ITBM connects to the electric trailer brakes through the 7-Way connector and controls the brake force through a Pulse Width Modulating (PWM) duty cycle.

The PWM is proportional to the rate of deceleration measured inside the ITBM. The ITBM controls the PWM output to the trailer brakes in four ways. The first occurs while the brake pedal becomes active and vehicle speed is greater than 0 km/h (0 mph). The second is the manual lever on the ITBM that can be controlled by the driver. If both the manual lever and the brake pedal are active simultaneously, the greater of the two, in terms of PWM output, will prevail. The third is after the vehicle has stopped moving, after approximately three seconds of the brake pedal applied the trailer brakes will be applied too. The vehicle uses Hill Start Assist (HSA) when on an incline. The fourth is that it will become active during an ESP trailer sway event.