C1100 — Definitions depend on the manufacturer

C1100: Definitions depend on the manufacturer — what it means, the affected system and what to check before replacing parts.

Meaning, symptoms, causes and checks

ABS Pump Switch Circuit Failure - Generic. Source catalogue definition; confirm applicability using vehicle service information.

Affected system: Chassis

Symptoms

  • Illuminated ABS warning light
  • Loss of anti-lock braking system function
  • Inoperative traction control system
  • Firm brake pedal feel or altered braking performance
  • Inability to clear diagnostic trouble codes

Possible causes

  • Faulty ABS pump relay or switch
  • Corroded or damaged wiring harness to the ABS pump
  • Blown fuse or tripped circuit breaker for the ABS motor
  • Internal failure of the ABS hydraulic control unit
  • Poor electrical ground connection at the pump module

What to check

  • Inspect the ABS fuse and relay for continuity and signs of overheating
  • Examine the pump motor electrical connector for corrosion or bent pins
  • Measure supply voltage at the pump motor terminals with the ignition on
  • Verify the ground circuit integrity for the ABS control module
  • Perform an active output test on the pump motor using a scan tool

Also written as: C1100-00, C110000 (some scan tools add the fault-type byte, e.g. -00).