Normal Operation

When the ignition key is turned to the ON position, the ABS module commands the Hydraulic Control Unit (HCU) pump on for 100 ms (±6 ms) and is then commanded off. After 6 ms, the ABS module reads the voltage that is being generated by the HCU pump. If the voltage indicates the motor is spinning at less than 500 rpm, there may be a locked motor. If this condition is detected 4 times, DTC C0020:12 sets. The pump motor is checked for an open circuit 2 seconds after the most recent successful pump motor off command. If the pump motor feedback remains greater than 0.75 volt for more than 50 ms (±6 ms) after these conditions have been met, DTC C0020:15 sets.

• DTC C0020:12 (ABS Pump Motor Control: Circuit Short To Battery) - sets in continuous memory and on-demand when the motor driver feedback voltage is less then battery voltage, that indicates an open driver or supply condition where the battery voltage is adjusted to the minimal threshold for the motor supply.
• DTC C0020:15 (ABS Pump Motor Control: Circuit Short To Battery Or Open) - sets in continuous memory and on-demand if the ABS pump feedback voltage is greater than 0.75 volts for more than 50 ms after the pump motor has been commanded off for 2 seconds or more, if there is an open or high resistance on the ABS pump motor circuit between the ABS module and the HCU, or if the ABS module is faulted internally.
• DTC C0020:71 (ABS Pump Motor Control: Actuator Stuck) - sets in continuous memory and on-demand if the ABS module detects that the ABS pump motor is not rotating when it is commanded to run.

This pinpoint test is intended to diagnose the following: 

• Fuse
• Wiring, terminals or connectors
• HCU
• ABS module