Mecatronic I/II

DESCRIPTION - The anti-lock brake system (ABS):
- is a four-wheel system which prevents wheel lockup by automatically modulating the brake pressure at each wheel independently during an emergency stop.
- enables the driver to maintain steering control and stopping in the shortest possible distance under most conditions.
- During normal braking, the ABS pedal feel will be the same as a conventional brake system.
- During ABS operation, a pulsation can be felt in the brake pedal accompanied with a fall and then a rise in the brake pedal height and a clicking sound.

OPERATION - The 4-wheel anti-lock brake system is optional equipment. The system operates as follows:
- Wheel lockup is prevented during an emergency stop by modulating brake pressure.
- Permits the driver to maintain steering control and stop the vehicle in the shortest possible distance under most conditions.
- The pedal effort and pedal feel during normal braking are similar to that of a conventional power-brake system.
- During the anti-lock brake operation, the driver will sense a pulsation in the brake pedal and a clicking sound.

COMPONENTS - The ABS has the following components;
- Power brake booster and brake master cylinder assembly.
- Brake pressure control valve.
- Hydraulic control unit (HCU), which includes a relay box and anti-lock brake control module.
- Front brake anti-lock sensor and rear brake anti-lock sensor.

POWER BRAKE BOOSTER - The diaphragm-type power brake booster:
- Is self-contained.
- Is mounted on the engine side of the cowl.
- Refer to Hydraulic System for brake booster information. Power Brake Assist

BRAKE MASTER CYLINDER
- The brake master cylinder is a tandem master cylinder.
- The ABS brake master cylinder uses only two outlet ports to supply the hydraulic control unit.
- The brake master cylinder has a plastic brake master cylinder reservoir with an integral fluid level switch.
- Refer to Hydraulic System for brake master cylinder information. Brake Master Cylinder

BRAKE PRESSURE CONTROL VALVE
- The brake pressure control valve controls the hydraulic pressure to the rear brakes to maintain a balance between the front and rear circuits.
- The brake pressure control valves are located on the hydraulic control unit.
- Each rear wheel brake has its own brake pressure control valve.
- Refer to Hydraulic System for brake pressure control valve information. Brake Proportioning/Combination Valve

HYDRAULIC CONTROL UNIT (HCU) - The hydraulic control unit is located below the brake master cylinder. The hydraulic control unit consists of:
- Electronic control unit with relays.
- A six-solenoid valve body for vehicles with ABS and traction control system; a four-solenoid valve body for vehicles without traction control system.
- Pump motor assembly.

CONTROL MODULE, ANTI-LOCK BRAKE
- The anti-lock brake control module is located on the hydraulic control unit (HCU).
- The HCU monitors and controls ABS operation.
- If a fault occurs in the ABS system a diagnostic trouble code (DTC) will be stored in memory.

BRAKE SENSOR, ANTI-LOCK
- The anti-lock brake sensor electrically senses each tooth of the anti-lock sensor indicator as it passes through the anti-lock brake sensor's magnetic field.
- This data is sent to the anti-lock brake control module. The anti-lock brake control module monitors the brake anti-lock sensors to determine wheel rotational speed.

TRACTION CONTROL - Traction control is available as an option on vehicles with optional ABS. The traction control system uses the following components in addition to the above ABS components. Refer to Traction Control System for information and serviceing. Antilock Brakes / Traction Control Systems

Throttle Control Actuator
- The throttle control actuator is located in the right front corner of the engine compartment.
- A throttle position sensor is mounted to the top of the throttle control actuator which communicates throttle position to the hydraulic control unit.
- Throttle function is controlled by the throttle control unit through two cables. One cable is attached to the accelerator pedal and to the throttle control unit. The other cable attaches to the throttle control unit and goes to the throttle body.
- The throttle control actuator controls throttle opening by effectively lengthening the cable to the throttle body, reducing the throttle opening for a given accelerator pedal position.

Traction Control Switch
- The traction control switch is located on the instrument panel, left of the steering column.
- When activated, the traction control switch disables the traction control system.
- To enable the traction control system, activate the traction control switch or the system will enable if the ignition switch is cycled off and on.