An Anti-lock Brake System (ABS) designated MK25 is available on 2003 to early production 2005 models. Later production 2005 vehicles feature an Anti-lock Brake System (ABS) designated MK25e.
The purpose of the Anti-lock Brake System (ABS) is to prevent wheel lockup under braking conditions on virtually any type of road surface. Antilock braking is desirable because a vehicle that is stopped without locking the wheels retains directional stability and some steering capability. This allows the driver to retain greater control of the vehicle during braking.
The Hydraulic Control Unit (HCU) and the Controller Antilock Brake (CAB), or Anti-lock Brake Module (ABM) as it is referred to on late model vehicles, used with this Anti-lock Brake System are combined (integrated) into one unit, which is called the Integrated Control Unit (ICU). The ICU is located below the master cylinder in the engine compartment. It is mounted to the left frame rail.
The ABS ICU consists of the following components: the CAB or ABM, eight (build/decay) solenoid valves (four inlet valves and four outlet valves) and one hydraulic pump motor.
The ABS ICU with traction control consists of the following components: the CAB, eight (build/decay) solenoid valves (four inlet valves and four outlet valves), two master cylinder isolation valves, two low pressure feed valves and one hydraulic pump motor.
The replaceable components of the ICU are the HCU and the CAB or ABM. No attempt should be made to service any individual components of the HCU or CAB/ABM.