C0020 — ABS pump motor fault

Causes

• Blown fuse or faulty relay for ABS pump motor supply
• Damaged or corroded electrical connector or wiring to the pump motor
• Open or shorted pump motor windings (motor internal failure)
• Faulty ABS hydraulic pump assembly (mechanical seizure or internal electronics)
• Faulty ABS control module or driver transistor
• Low battery voltage or poor main battery connections

Symptoms

• ABS warning lamp illuminated on dash
• Traction control/ESC warning may also be lit
• Unusual or no noise from the ABS pump when ABS is commanded (should normally run briefly)
• Reduced or altered brake feel under ABS activation (skidding may occur)
• Stored ABS/ESP related fault codes in the ABS control module

What to check

• Read and record all ABS and powertrain DTCs with a capable scan tool, including freeze frame if available
• Verify vehicle battery state of charge and measure battery voltage with engine off and cranking
• Visually inspect ABS pump electrical connector and wiring harness for corrosion, damaged insulation, burned pins or water ingress
• Check ABS pump/ECU fuses and relays for continuity and correct operation
• Listen for pump operation when commanding ABS pump with scan tool or during ABS self-test
• Check for other ABS-related codes (wheel speed sensors, communications) that may be related

Signal parameters

• Nominal supply voltage to pump: ~12 V (engine running typically 13–14.5 V)
• Expected idle motor current: varies by model; typical range 4–20 A when running (consult OEM spec)
• Motor winding resistance (cold): low ohms (typically
• Control module command signal: digital/ground drive; verify switching to ground or 12 V per OEM wiring diagram
• No-load running RPM or motor duty cycle reported by ABS module (if available)

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