Code
C0628
Generic
C — Chassis
Variable Effort Steering Module Performance
Views:
UK: 25
EN: 37
RU: 31
AI status
Completed
Completed
100%
Causes
- Intermittent or low power supply to the steering module (battery, fuse, fusible link)
- Poor ground or corroded/loose connector at the steering module
- Damaged wiring harness (short, open, high resistance) between module and sensors/motor
- Faulty steering torque sensor, steering angle sensor, or steering position sensor
- Faulty steering assist motor or motor driver electronics inside the module
- CAN bus or LIN communications errors between steering module and other control modules
Symptoms
- Steering assist reduced, harsh, or inconsistent (heavier or lighter than expected)
- Illumination of steering or stability warning lamp(s)
- Steering warning message or reduced functionality displayed in instrument cluster
- Intermittent assist loss or assist that varies with vehicle speed/conditions
- Possible steering angle or stability control faults set concurrently
What to check
- Read stored and pending DTCs and freeze/frame data from steering module and other chassis modules
- Inspect fuses, fusible links, and relay(s) that supply the steering module
- Visually inspect connectors and wiring at the steering module, torque sensor, angle sensor, and motor for corrosion, pin damage, or looseness
- Check battery state of charge and charging system (alternator) voltage under load
- Use a scan tool to monitor live data: module supply voltage, ground integrity, steering torque, steering angle, motor current/command, and CAN status
- Check for related communications DTCs (U-codes) indicating bus faults or missing modules
Signal parameters
- Module supply voltage: typical 12 V system voltage within normal range (approx. 11–15 V) during operation
- Reference/logic supply: 5 V reference present for sensors (when applicable)
- Steering torque sensor output: centered idle value and changing smoothly with applied steering torque
- Steering angle/position: consistent and changing with wheel movement; no large jumps or implausible values
- Motor driver output: PWM/drive command present when assist is requested; motor current increases with steering effort
- CAN/LIN network messages: module present on network and transmitting expected messages; low error/frame counts
Diagnostic algorithm
- Retrieve all DTCs and freeze frame data from the steering module and related modules. Note when the fault occurs (speed, temperature, steering input).
- Inspect power and ground circuits: check fuses, measure battery voltage at the steering module connector, and verify a good chassis/ground connection.
- Visually inspect wiring and connectors for damage, corrosion, or pushed-out pins. Wiggle test wiring while monitoring live data for changes.
- Use a scan tool to view live parameters: steering torque, steering angle, motor current/command, module supply and internal status. Look for implausible values or rapid changes.
- Check network communication: verify the steering module appears on CAN/LIN and no network-related U-codes are present. If communications are missing, isolate bus wiring and termination.
- Test sensors: confirm steering torque and angle sensors produce smooth, proportional signals while turning the wheel. Compare against manufacturer reference where available.
- Check for mechanical binding: with vehicle secure, turn the steering wheel and check for friction/noise in column/rack, and check wheel bearings and tie rods for binding.
- If electrical supply, grounds, wiring, sensors and mechanical condition are good but fault persists, attempt module reset/calibration per manufacturer procedure. Reflash/update module software if updates are available.
- If module still reports performance fault after above checks, consider bench test or replacement of the steering module or motor assembly. Replace only after confirming root cause to avoid unnecessary replacement.
- After repair or replacement, clear DTCs and perform required calibrations and a test drive to verify repair.
Likely causes
- Loss or intermittency of module supply or ground
- Corroded or damaged connector at the steering module
- Failed torque/angle sensor providing implausible signals
- Internal electronic failure in module motor driver or controller
- Communication fault on vehicle network preventing assist requests or feedback
Fault status
Status
Variable Effort Steering Module reports a performance fault — steering assist may be reduced or inconsistent. Module may request service or set related stability/steering warnings.
Repair difficulty: Medium
Diagnostic time: 1.5-3.0 hours
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Code
C0628
HUMMER
C — Chassis
Level Control Position Sensor Circuit High
Views:
UK: 18
EN: 27
RU: 18
AI status
Completed
Completed
100%
Causes
- Intermittent or low power supply to the steering module (battery, fuse, fusible link)
- Poor ground or corroded/loose connector at the steering module
- Damaged wiring harness (short, open, high resistance) between module and sensors/motor
- Faulty steering torque sensor, steering angle sensor, or steering position sensor
- Faulty steering assist motor or motor driver electronics inside the module
- CAN bus or LIN communications errors between steering module and other control modules
Symptoms
- Steering assist reduced, harsh, or inconsistent (heavier or lighter than expected)
- Illumination of steering or stability warning lamp(s)
- Steering warning message or reduced functionality displayed in instrument cluster
- Intermittent assist loss or assist that varies with vehicle speed/conditions
- Possible steering angle or stability control faults set concurrently
What to check
- Read stored and pending DTCs and freeze/frame data from steering module and other chassis modules
- Inspect fuses, fusible links, and relay(s) that supply the steering module
- Visually inspect connectors and wiring at the steering module, torque sensor, angle sensor, and motor for corrosion, pin damage, or looseness
- Check battery state of charge and charging system (alternator) voltage under load
- Use a scan tool to monitor live data: module supply voltage, ground integrity, steering torque, steering angle, motor current/command, and CAN status
- Check for related communications DTCs (U-codes) indicating bus faults or missing modules
Signal parameters
- Module supply voltage: typical 12 V system voltage within normal range (approx. 11–15 V) during operation
- Reference/logic supply: 5 V reference present for sensors (when applicable)
- Steering torque sensor output: centered idle value and changing smoothly with applied steering torque
- Steering angle/position: consistent and changing with wheel movement; no large jumps or implausible values
- Motor driver output: PWM/drive command present when assist is requested; motor current increases with steering effort
- CAN/LIN network messages: module present on network and transmitting expected messages; low error/frame counts
Diagnostic algorithm
- Retrieve all DTCs and freeze frame data from the steering module and related modules. Note when the fault occurs (speed, temperature, steering input).
- Inspect power and ground circuits: check fuses, measure battery voltage at the steering module connector, and verify a good chassis/ground connection.
- Visually inspect wiring and connectors for damage, corrosion, or pushed-out pins. Wiggle test wiring while monitoring live data for changes.
- Use a scan tool to view live parameters: steering torque, steering angle, motor current/command, module supply and internal status. Look for implausible values or rapid changes.
- Check network communication: verify the steering module appears on CAN/LIN and no network-related U-codes are present. If communications are missing, isolate bus wiring and termination.
- Test sensors: confirm steering torque and angle sensors produce smooth, proportional signals while turning the wheel. Compare against manufacturer reference where available.
- Check for mechanical binding: with vehicle secure, turn the steering wheel and check for friction/noise in column/rack, and check wheel bearings and tie rods for binding.
- If electrical supply, grounds, wiring, sensors and mechanical condition are good but fault persists, attempt module reset/calibration per manufacturer procedure. Reflash/update module software if updates are available.
- If module still reports performance fault after above checks, consider bench test or replacement of the steering module or motor assembly. Replace only after confirming root cause to avoid unnecessary replacement.
- After repair or replacement, clear DTCs and perform required calibrations and a test drive to verify repair.
Likely causes
- Loss or intermittency of module supply or ground
- Corroded or damaged connector at the steering module
- Failed torque/angle sensor providing implausible signals
- Internal electronic failure in module motor driver or controller
- Communication fault on vehicle network preventing assist requests or feedback
Fault status
Status
Variable Effort Steering Module reports a performance fault — steering assist may be reduced or inconsistent. Module may request service or set related stability/steering warnings.
Repair difficulty: Medium
Diagnostic time: 1.5-3.0 hours
Similar codes
Repair manuals
Manual library for HUMMER
69
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HUMMER
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