Electronic Braking System
This vehicle is equipped with an Electronic Brake System (EBS). The EBS constantly monitors air pressure and deceleration, actively changing and regulating the air pressure of the brakes regardless of foot position. This allows for the driver to more easily brake on inclines, on declines, and in emergency situations, providing a smoother stop. When using the foot pedal to brake, the EBS analyzes how much the pedal is pressed down and applies the appropriate amount of air to achieve the request of the driver.
Important: For proper EBS system operation, do not alter the size of tires, brake pads, or brake chambers. These values are programmed into the electronic control unit, and a change in value could result in a difference in braking force. Take your vehicle to an authorized Freightliner dealer for any removal and replacement of these parts.
The pressure of both the primary and secondary system appear on the air reservoir pressure gauge on the driver display.
If air pressure drops below approximately 70 psi (483 kPa) in either system, a warning telltale illuminates. See Brake System Indicators and Messages. If the park brake is not set, an audible alert also activates.
Important: In the event that the driver pulls but then releases the park brake control switch while in motion, the system will attempt to repressurize the air supply system in order to re-release tractor and trailer parking brakes. However, such repressurization may not be possible (for example, depending how much air has been evacuated from the trailer air system). If conditions limit the system from repressurizing the trailer air system within 3 seconds, then the system may re-exhaust the trailer park brake air supply to apply the trailer brakes thereby bringing the vehicle to a halt.
Before a vehicle with insufficient brake system air pressure can be moved, the spring parking brakes must be released by applying an external air source at the gladhands, or by manually caging the parking brake springs.
Warning: Do not cage the spring parking brakes and then drive the vehicle. If this is attempted, there will be no way to hold the vehicle stationary after coming to a complete stop and releasing the service brake pedal. This could result in serious personal injury or vehicle damage. Before releasing the spring parking brakes, make the connection to a towing vehicle or chock the tires.
Once the brake system is operating properly again, uncage the spring parking brakes before resuming normal vehicle operation.
Emergency Pneumatic Back-Up System
If there is a malfunction in the EBS, a warning with the red EBS symbol activates. During a malfunction where the EBS is disabled and the vehicle must be brought to a safe stop, the brake system operates as a traditional pneumatic brake system. This means that the pedal delivers air pressure to the brake chambers directly. If the EBS is disabled, the Antilock Brake System (ABS) is also disabled, but the brakes can be pumped to perform manual antilock braking.
Warning: Do NOT attempt to use the emergency pneumatic back-up system to continue driving. This system should only be used to bring the vehicle to a safe stop when the EBS malfunctions. Once the vehicle is brought to a safe stop, tow the vehicle to the nearest authorized Freightliner dealer for repair.