C1090

Code

Generic C — Chassis

ABS pump motor circuit malfunction

Brand: Generic

Type: C — Chassis

Views: UK: 19 EN: 32 RU: 26

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Read and record all ABS trouble codes and freeze frame with a capable scan tool
Verify battery voltage (key on/off and during cranking) — low voltage can cause faults
Inspect fuses and relays for the ABS pump circuit; swap relay if possible
Visually inspect pump motor connector and wiring for corrosion, damage, or water ingress
Measure voltage at the pump motor power terminal with key on / during commanded pump operation
Check continuity and resistance of motor supply and ground circuits

Battery supply to pump: nominal ~12 V with key on; should remain >11 V under load
Pump motor coil resistance: typically low (example ranges 0.2–10 Ω depending on vehicle) — consult OEM spec
Pump current draw during operation: often several amps — common range 5–30 A (varies by vehicle)
Control output from ABS module: may be direct switched 0–12 V or PWM (0–12 V duty cycle); frequency often tens to hundreds of Hz
Open-circuit (infinite Ω) indicates wiring open; near-zero Ω to chassis indicates short to ground

Connect a scan tool, read and save ABS codes and live data. Note any related codes (sensors, relays, power).
Check battery state of charge and terminal/ground condition. Charge or replace battery if low; clean terminals.
Inspect fuses and relay for the ABS pump circuit. Replace suspect fuses/relays and retest.
Visually inspect the ABS pump motor connector and wiring harness for corrosion, damage, pin push-out, or water intrusion. Repair as needed.
With connector disconnected, measure supply voltage at the harness power pin (key on). If no power, trace back to fuse/relay and repair.
Verify ground continuity from pump motor ground terminal to chassis/battery negative. Repair poor grounds.
Measure pump motor coil resistance at the motor terminals (engine off). Compare to spec; a very high or open reading indicates a failed motor.
Reconnect and command the pump on with a scan tool while monitoring voltage and current. If command output from module is present but motor does not run and motor has correct supply voltage, suspect motor or high current fault.
If module driver output is absent or abnormal (no switching / stuck low/high), inspect wiring for shorts and consider ABS module fault. Check for intermittent connections by gently moving harness while observing live data.
After repairs, clear codes and perform a road test and ABS self-check to confirm proper operation and that code does not return.