Chassis, generic

C05AE ABS Pump Motor Calibration Not Learned

Check engine lightOn
EmissionsNot relevant
Drive cycleRequired
Limp modePossible

C05AE means the brake module lacks a valid zero calibration for the measuring channels of its pump motor. In GM's 2016 and 2019 hybrid brake module (BSC1) the motor voltages are read through a sigma-delta modulator that needs a 0 V calibration; with the ignition on, more than 6.9 V system voltage and the pump off, the code sets if the raw generator voltage reading falls outside 14–23.8 or the drop across the pump relay outside 13–18, for 3 s. A second test flags supply undervoltage: shunt voltage under 7.5 V or relay drain voltage outside 1.5–3 V for 2 s. Type A with MIL; the check passes after 20 s of driving above 18.6 mph. Such offset calibration is standard for delta-sigma converters, as TI's ADS131M04 data sheet shows.

Likely causes

Stored zero calibration missing or invalid after module replacement or programming
Low or unstable supply voltage during the calibration
Pump motor relay or shunt in the module out of tolerance

Symptoms

  • ABS and brake warning lamps plus check engine lamp
  • ABS or stability functions limited until the calibration succeeds

Repair estimate

DifficultyHardWorkshop job
Parts and labour€50–2,000
Time0.3–3 h

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

Parts involved

abs pump motorabs module

Related codes

C052BC052DC052FC055BC05AA

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