Antilock Brakes / Traction Control Systems: Service Precautions
Safety Precautions
The anti-lock brake system uses an electronic control module known as the anti-lock brake module. This module is designed to withstand normal current draws associated with vehicle operation. Care must be taken to avoid overloading the circuits.
Volkswagen does not manufacture any vehicles or replacement parts that contain asbestos. Aftermarket products may or may not contain asbestos. Refer to aftermarket product packaging for product information.
Whether the product contains asbestos or not, dust and dirt can accumulate on brake parts during normal use. Follow practices prescribed by appropriate regulations for the handling, processing and disposing of dust and debris.
• In testing for open or short circuits, do not ground or apply voltage to any of the circuits unless instructed to do so for a diagnostic procedure.
• These circuits should only be tested using a high impedance multi-meter or the designated scan tool as described in this section. Power should never be removed or applied to any control module with the ignition in the ON position. Before removing or connecting battery cables, fuses, or connectors, always turn the ignition to the OFF position.
• The ABM 47-way connector should never be connected or disconnected with the ignition switch in the ON position.
• This vehicle utilizes active wheel speed sensors. Do not apply voltage to wheel speed sensors at any time.
• Use only factory wiring harnesses. Do not cut or splice wiring to the brake circuits. The addition of aftermarket electrical equipment (car phone, radar detector, citizen band radio, trailer lighting, trailer brakes, ETC.) on a vehicle equipped with anti-lock brakes may affect the function of the anti-lock brake system.
• When performing any service procedure on a vehicle equipped with ABS, do not apply a 12 volt power source to the ground circuit of the pump motor in the HCU. Doing this will damage the pump motor and will require replacement of the entire HCU.
• An attempt to remove or disconnect certain system components may result in improper system operation. Only those components with approved removal and installation procedures in this manual should be serviced.
• If welding work is to be performed on the vehicle using an electric arc welder, the ABM connector should be disconnected during the welding operation.
• Many components of the ABS are not serviceable and must be replaced as an assembly. Do not disassemble any component which is not designed to be serviced.
• Brake fluid will damage painted surfaces. If brake fluid is spilled on any painted surface, wash off with water immediately.
• Only the recommended jacking or hoisting positions for this vehicle are to be used whenever it is necessary to lift a vehicle.
• During service procedures, grease or any other foreign material must be kept off brake shoes and braking surfaces of brake rotor or drum, and external surfaces of hub and bearing assembly.
• Brake rotor and caliper handling must be done in such a way as to avoid damage to the rotor, especially the machined surfaces, and scratching or nicking of the brake linings.
• Only the recommended jacking or hoisting procedures for this vehicle are to be used whenever it is necessary to lift a vehicle. Failure to raise a vehicle utilizing the recommended lift points can result in damage to the vehicle.