Chassis, generic

C052D ABS Pump Motor Control Circuit High

Check engine lightUsually off
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

The pump motor control circuit reads higher than the commanded state allows, which normally means the control line or motor terminal is shorted toward battery voltage or the switching stage is stuck on. No manufacturer publishes this code; Mitsubishi, for example, reports its pump motor faults under C052B and C052C. The Bosch fault-monitoring patent US5329238 shows the principle: terminal voltages are compared with supply-referenced limits, a level above the upper one is taken as a short to plus, and the drive is then cut. With a stuck-on stage the pump may hum continuously and drain the 12 V battery. The US brake standard FMVSS 135 requires a warning for any electrical ABS failure; normal braking without ABS remains.

Likely causes

Motor relay or semiconductor switch in the ABS unit stuck closed
Motor lead or control line shorted to battery voltage
Moisture bridging pins in the ABS connector

Symptoms

  • ABS warning lamp on
  • Pump motor runs continuously or hums with ignition on
  • Battery discharged after standing

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–2,000
Time0.5–4 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

abs pump motormotor wiring

Related codes

C052BC052CC052E

References: patents.google.com, mitsubishitechinfo.com, law.cornell.edu.