This vehicle is equipped with the Continental Teves MK-50 antilock braking system or antilock braking system/traction control system (w/NW9).

The following components are involved in the operation of the above system.

The EBCM performs one initialization test each ignition cycle. The initialization of the EBCM occurs when the following conditions are met:

The initialization sequence briefly cycles each solenoid and the pump motor to verify proper operation of the components. The EBCM sets one or more DTCs in accordance with any malfunction that is detected.

When wheel slip is detected during a brake application, the ABS enters antilock mode. During antilock braking, hydraulic pressure in the individual wheel circuits is controlled to prevent any wheel from slipping. A separate hydraulic line and specific solenoid valves are provided for each wheel. The ABS can decrease, hold, or increase hydraulic pressure to each wheel brake. The ABS cannot, however, increase hydraulic pressure above the amount which is transmitted by the master cylinder during braking.

During antilock braking, a series of rapid pulsations is felt in the brake pedal. These pulsations are caused by the rapid changes in position of the individual solenoid valves as the EBCM responds to wheel speed sensor inputs and attempts to prevent wheel slip. These pedal pulsations are present only during antilock braking and stop when normal braking is resumed or when the vehicle comes to a stop. A ticking or popping noise may also be heard as the solenoid valves cycle rapidly. During antilock braking on dry pavement, intermittent chirping noises may be heard as the tires approach slipping. These noises and pedal pulsations are considered normal during antilock operation.

Vehicles equipped with ABS may be stopped by applying normal force to the brake pedal. Brake pedal operation during normal braking is no different than that of previous non-ABS systems. Maintaining a constant force on the brake pedal provides the shortest stopping distance while maintaining vehicle stability.

The EBCM closes the isolation valve and keeps the dump valve closed in order to isolate the slipping wheel when wheel slip occurs. This holds the pressure steady on the brake so that the hydraulic pressure does not increase or decrease.

If a pressure hold does not correct the wheel slip condition, a pressure decrease occurs. The EBCM decreases the pressure to individual wheels during deceleration when wheel slip occurs. The isolation valve is closed and the dump valve is opened. The excess fluid is stored in the accumulator until the pump can return the fluid to the master cylinder or fluid reservoir.

After the wheel slip is corrected, a pressure increase occurs. The EBCM increases the pressure to individual wheels during deceleration in order to reduce the speed of the wheel. The isolation valve is opened and the dump valve is closed. The increased pressure is delivered from the master cylinder.

The dynamic rear proportioning (DRP) is a control system that replaces the hydraulic proportioning function of the mechanical proportioning valve in the base brake system. The DRP control system is part of the operation software in the EBCM. The DRP uses active control with existing ABS in order to regulate the vehicle's rear brake pressure.

The red brake warning indicator is illuminated when the dynamic rear proportioning function is disabled.

Vehicles equipped with NW9 have added EBCM software and an extra solenoid to perform traction control. The traction control system (TCS) uses active braking to transfer torque to the drive wheel with the most traction during a TCS event. When drive wheel slip is detected by the EBCM during accelleration, the TCS cutout solenoid is energized to close the TCS cutout valve. This isolates the rear brake hydraulic circuits so that pressure can be applied to a rear brake without forcing fluid pressure back to the master cylinder. The EBCM then energizes the ABS pump motor and directs fluid through the BPMV to the slipping wheel. Torque is then transferred through the differential to the wheel that is not slipping. The low traction indicator illuminates whenever the TCS is active.

When the vehicle is experiencing an ABS event, the EBCM temporarily disables the exhaust brake. This is done to help ensure that vehicle control and stability is maintained. Ground to the exhaust brake relay coil is normally supplied through the EBCM. The EBCM opens this ground circuit during an ABS event.

The instrument panel cluster (IPC) illuminates the brake warning indicator when any of the following occurs.

The IPC illuminates the ABS indicator when any of the following occurs.

LOW TRACTION

The low traction indicator is part of the traction control switch. The EBCM applies ground to the traction control active signal circuit in order to illuminate the low traction indicator during a traction control event.

TRACTION OFF

The traction off indicator, which is part of the traction control switch, turns OFF when ground is applied to the service traction control signal circuit. The EBCM illuminates the traction off indicator if any of the following conditions are present.