I would pull the fuse for the ABS hydraulic pump and then put it back in and see what happens. Don't ever recall a pump running. Dealer may need to hook up scan tool for diagnostic fault codes, DTCs.
Principles of Operation
The ABS control module receives wheel speed readings from both front wheel speed sensors and the rear differential speed sensor, and processes this information to determine if an ABS event is necessary. The wheel speed sensor electrically senses each tooth of the ABS sensor indicators as it passes through the wheel speed sensor's magnetic field.
The ABS control module continuously monitors and compares the rotational speed of each wheel speed sensor indicator and, when it detects an impending wheel lock, modulates brake pressure to the appropriate brake caliper(s). This is accomplished by triggering the hydraulic control unit (HCU) to open and close the appropriate solenoid valves. Once the affected wheel returns to normal speed, the ABS control module returns the solenoid valves to their normal position, and normal (base) braking resumes.
The ABS control module is self-monitoring. When the ignition switch is turned to the RUN position, the ABS control module will do a preliminary electrical check, and at approximately 20 km/h (12 mph), the pump motor is turned on for approximately one-half second. Any malfunction of the ABS system will cause the ABS to shut off; normal power assisted braking, however, remains.
Inspection and Verification — Scan Tool Communications Check
- Verify the customer concern by carrying out the Drive Cycle Test.
- Visually inspect for obvious signs of mechanical and electrical damage.
Visual Inspection Chart
- Parking brake cable
- Tire pressure
- Tire size or mismatched tires
- Blown fuse
- Central junction box (CJB):
- Battery junction box
- Connectors or connections
- Ground integrity
- Harness routing
- Wire chafing
- Circuitry open/shorted
The four-wheel anti-lock brake system (4WABS) consists of the following components:
- Anti-lock brake control module (2C265)
- Front anti-lock brake sensor (2C204)
- Front anti-lock brake sensor indicator (2C182)
- Hydraulic control unit (2C219)
- Rear anti-lock brake sensor (2C190)
- Rear anti-lock brake sensor indicator (2C189)
- Yellow ABS warning indicator