Antilock Brake System Components

MASTER CYLINDER AND POWER BRAKE BOOSTER
The following is a detailed description of the antilock brake system components.

Three different master cylinders are used depending on whether or not the ABS system is equipped with traction control.

Master Cylinder And Power Brake Booster:

A vehicle equipped with ABS without traction control uses the same type of master cylinder as a vehicle without antilock brakes.

A vehicle equipped with ABS with traction control uses a unique center port master cylinder.

A vehicle equipped with All Wheel Drive (AWD) (which have four-wheel disc brakes) and ABS (without traction control) also uses a unique master cylinder. The master cylinder used on this vehicle has a piston bore diameter which is larger than the master cylinder used on the other brake applications.

Master cylinders on vehicles with traction control use ISO fittings at the outlet ports, while vehicles without traction control use standard double inverted flares.

The brake tubes from the primary and secondary outlet ports on the master cylinder go directly to the Hydraulic Control Unit (HCU).

Service is the same on all master cylinders.

All vehicles use a common power brake booster, except model equipped with AWD. Service is the same on all boosters.

INTEGRATED CONTROL UNIT (ICU)

Integrated Control Unit (ICU):

ICU Mounting Location:

The Hydraulic Control Unit (HCU) and the Controller Antilock Brake (CAB) used with this antilock brake system are combined (integrated) into one unit, which is called the Integrated Control Unit (ICU). The ICU is located on the driver's side of the front suspension cradle under the vehicle.

Two different HCUs and CABs are used on this vehicle depending on whether or not the vehicle is equipped with traction control. The HCU on a vehicle equipped with ABS and traction control has a valve block housing that is approximately 1 inch longer on the low pressure fluid accumulators side than a HCU on a vehicle that is equipped with only ABS.

The ABS-only ICU consists of the following components: the CAB, eight (build/decay) solenoid valves (four inlet valves and four outlet valves), valve block, fluid accumulators. a pump and an electric motor.

The ABS with traction control ICU consists of the following components: the CAB, eight (build/decay) solenoid valves (four inlet valves and four outlet valves), two hydraulic shuttle valves, two ASR valves, valve block, fluid accumulators, a pump, and an electric pump/motor. On vehicles with traction control, the ICU contains 10 solenoid valves. The two ASR valves and solenoids are used to isolate the brake system during traction control operation.

The replaceable components of the ICU are the HCU and the CAB. No attempt should be made to service any individual components of the HCU or CAB.