Chassis, generic

C05A3 Wheel Speed Sensors Supply Circuit High

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

Active wheel speed sensors are fed by the ABS module and send their pulses back as a current on the same pair of wires, as HELLA explains. C05A3 reports that this common supply is too high or cannot be switched off. GM's 2016 and 2019 hybrid brake controllers look for reverse current on the supply line, the sign of a short to the battery feed, for over 3.5 s. A 2019 GM EBCM with a system ASIC uses C05A3 for two cases: the sensor supply exceeds its overvoltage limit, after which the ASIC turns off all four high-side switches, and a periodic test in which a supposedly switched-off high side is still live. Both are Type A with MIL. Allegro rates its wheel speed sensor IC for 24 V and clamps at 28 V. With no wheel speeds, ABS, ESC and traction control stop working.

Likely causes

Wheel speed sensor wire chafed and shorted to battery voltage
Supply switch or ASIC in the brake module stuck on
Water in a wheel speed sensor connector bridging to a powered circuit

Symptoms

  • ABS, traction and stability control warning lamps on at the same time
  • Several or all wheel speed signals lost, speedometer may drop out
  • MIL on (GM)

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–1,200
Time0.5–3 h

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

Parts involved

wss supplywheel speed sensorabs control module

Related codes

C05A4C0500C0503C0565

References: gsi.ext.gm.com, gsi.ext.gm.com, gsi.ext.gm.com, hella.com.