Code
C0563
Generic
C — Chassis
ABS Control Module Performance
AI status
Completed
Completed
100%
Causes
- Low or intermittent battery voltage / poor battery condition
- Poor power supply or ground connection to the ABS control module
- Corroded, loose or damaged connectors or wiring harness to ABS module
- Loss of CAN/vehicle communication to the ABS module
- Faulty wheel speed sensors or damaged tone rings
- Faulty ABS hydraulic pump, motor or solenoid valves
Symptoms
- ABS warning lamp illuminated (may be constant or intermittent)
- Traction control / ESC lamp may also illuminate
- ABS may not activate during hard braking; vehicle may lock wheels
- Unusual pump operation (runs continuously or not at all)
- Reduced or altered braking/traction control performance
- Possible loss of communication messages on diagnostic scan tool
What to check
- Read all stored and pending DTCs including U-codes and freeze frame data
- Check battery voltage (engine off and cranking) and charging system
- Inspect ABS module connectors, pins and wiring for corrosion, damage, or looseness
- Verify power feed and ground continuity at the ABS module
- Scan CAN bus for communication errors and check for lost messages
- Check wheel speed sensor signals (voltage/pulse or frequency) at each sensor and at the module
Signal parameters
- Module supply voltage (KOEO): ~11–14 V (should be stable)
- Ignition-switched power: present with key on, typically ~12 V
- Ground: low resistance to chassis ground (near 0 ohms)
- CAN High/Low idle voltages: approx. 2.5 V common mode; differential ~0 V idle, ~2–3 V during active comms
- Wheel speed sensor (passive) AC amplitude: increases with wheel speed; typical 0.1–2.0 V RMS at low speed and higher at speed
- Wheel speed sensor (active/Hall) digital: 0–5 V square wave or 0.5–4.5 V with frequency proportional to speed
Diagnostic algorithm
- Connect a capable scan tool, record all ABS and related U/P codes and freeze frame data. Do not erase initially.
- Verify battery state-of-charge and charging system health. Charge or replace battery if low.
- Visually inspect ABS module, connectors, harness, and associated grounds for corrosion, water ingress, or damage. Repair as needed.
- With ignition ON, back-probe the ABS module power and ground pins. Confirm stable supply voltage and good ground continuity while wiggling connectors to check for intermittent faults.
- Check CAN bus communication at the module using a scope or multimeter. Look for proper idle voltages and message activity; compare to other modules.
- Test each wheel speed sensor signal at the sensor and at the module input while rotating the wheel (hand spin or road test). Verify expected waveform, amplitude, and frequency. Replace sensors or repair tone rings if signals are missing or erratic.
- Inspect tone rings and reluctors for damage, missing teeth, or excessive air gap. Repair or replace as required.
- Check ABS pump motor and valve solenoid operation and current draw. If pump does not run or draws abnormal current, test supply, relay, and control outputs.
- Clear codes and perform a controlled test drive or on-lift wheel spin test to attempt to re-create the fault. Monitor live data for dropouts or anomalies.
- If wiring and sensors check good but fault persists, check for available ABS control module software updates or TSBs. Reflash or update per manufacturer procedures if available.
- If module is confirmed faulty after verification of power, grounds, communication and sensor inputs, replace or repair ABS control module and program/configure to vehicle. Recheck system operation and clear codes.
- After repair, perform full function test including ABS activation and road test to verify fault is resolved.
Likely causes
- Poor power/ground at the ABS control module
- CAN bus communication error between ABS module and main ECU
- Failed or intermittent wheel speed sensor feeding incorrect inputs
- Internal ABS module fault (electronics or firmware)
Fault status
Status
ABS control module reported a performance fault. Check power, ground, connectors, CAN communication, wheel speed sensors and hydraulic components. Intermittent wiring or a failed module are common causes; replacement and programming may be required after verification.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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Code
C0563
HUMMER
C — Chassis
Calibration ROM Checksum Error
AI status
Completed
Completed
100%
Causes
- Low or intermittent battery voltage / poor battery condition
- Poor power supply or ground connection to the ABS control module
- Corroded, loose or damaged connectors or wiring harness to ABS module
- Loss of CAN/vehicle communication to the ABS module
- Faulty wheel speed sensors or damaged tone rings
- Faulty ABS hydraulic pump, motor or solenoid valves
Symptoms
- ABS warning lamp illuminated (may be constant or intermittent)
- Traction control / ESC lamp may also illuminate
- ABS may not activate during hard braking; vehicle may lock wheels
- Unusual pump operation (runs continuously or not at all)
- Reduced or altered braking/traction control performance
- Possible loss of communication messages on diagnostic scan tool
What to check
- Read all stored and pending DTCs including U-codes and freeze frame data
- Check battery voltage (engine off and cranking) and charging system
- Inspect ABS module connectors, pins and wiring for corrosion, damage, or looseness
- Verify power feed and ground continuity at the ABS module
- Scan CAN bus for communication errors and check for lost messages
- Check wheel speed sensor signals (voltage/pulse or frequency) at each sensor and at the module
Signal parameters
- Module supply voltage (KOEO): ~11–14 V (should be stable)
- Ignition-switched power: present with key on, typically ~12 V
- Ground: low resistance to chassis ground (near 0 ohms)
- CAN High/Low idle voltages: approx. 2.5 V common mode; differential ~0 V idle, ~2–3 V during active comms
- Wheel speed sensor (passive) AC amplitude: increases with wheel speed; typical 0.1–2.0 V RMS at low speed and higher at speed
- Wheel speed sensor (active/Hall) digital: 0–5 V square wave or 0.5–4.5 V with frequency proportional to speed
Diagnostic algorithm
- Connect a capable scan tool, record all ABS and related U/P codes and freeze frame data. Do not erase initially.
- Verify battery state-of-charge and charging system health. Charge or replace battery if low.
- Visually inspect ABS module, connectors, harness, and associated grounds for corrosion, water ingress, or damage. Repair as needed.
- With ignition ON, back-probe the ABS module power and ground pins. Confirm stable supply voltage and good ground continuity while wiggling connectors to check for intermittent faults.
- Check CAN bus communication at the module using a scope or multimeter. Look for proper idle voltages and message activity; compare to other modules.
- Test each wheel speed sensor signal at the sensor and at the module input while rotating the wheel (hand spin or road test). Verify expected waveform, amplitude, and frequency. Replace sensors or repair tone rings if signals are missing or erratic.
- Inspect tone rings and reluctors for damage, missing teeth, or excessive air gap. Repair or replace as required.
- Check ABS pump motor and valve solenoid operation and current draw. If pump does not run or draws abnormal current, test supply, relay, and control outputs.
- Clear codes and perform a controlled test drive or on-lift wheel spin test to attempt to re-create the fault. Monitor live data for dropouts or anomalies.
- If wiring and sensors check good but fault persists, check for available ABS control module software updates or TSBs. Reflash or update per manufacturer procedures if available.
- If module is confirmed faulty after verification of power, grounds, communication and sensor inputs, replace or repair ABS control module and program/configure to vehicle. Recheck system operation and clear codes.
- After repair, perform full function test including ABS activation and road test to verify fault is resolved.
Likely causes
- Poor power/ground at the ABS control module
- CAN bus communication error between ABS module and main ECU
- Failed or intermittent wheel speed sensor feeding incorrect inputs
- Internal ABS module fault (electronics or firmware)
Fault status
Status
ABS control module reported a performance fault. Check power, ground, connectors, CAN communication, wheel speed sensors and hydraulic components. Intermittent wiring or a failed module are common causes; replacement and programming may be required after verification.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
Repair manuals
Manual library for HUMMER
138
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