Pinpoint Test H : Abs (Anti-Lock Brake System) Pump Motor Control Circuit Faults: Notes
Refer to VEHICLE DYNAMIC SYSTEMS for schematic and connector information.
Normal Operation and Fault Conditions
The ABS module uses an internal solid state switch to operate the hydraulic pump motor. The ABS module tests the hydraulic pump motor by activating it for 30 milliseconds. The ABS module monitors the voltage drop across the hydraulic pump motor while is being activated. After 30 milliseconds have passed, the ABS module stops applying voltage to the pump motor and monitors the voltage the spinning hydraulic pump motor is generating and the voltage drop across the hydraulic pump motor solid state switch. If the monitored voltages are not within the specifications, the ABS module sets one or more Diagnostic Trouble Codes (DTCs).
The SOBDMC monitors fault messages from the ABS module. When the ABS module sets DTC C0020:13 or C0020:71, the SOBDMC sets a DTC and illuminates the MIL.
DTC Fault Trigger Conditions
| DTC | Description | Fault Trigger Conditions |
|---|---|---|
| C0020:12 | ABS Pump Motor Control: Circuit Short to Battery | This DTC sets in continuous memory and on-demand if the module detects more than 0.93 volt for longer than 3 seconds from the pump motor once the pump motor has been deactivated. |
| C0020:13 | ABS Pump Motor Control: Circuit Open | This DTC sets in continuous memory and on-demand if the voltage supplied to the ABS module is less than 10 volts, 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. |
| C0020:71 | ABS Pump Motor Control: Actuator Stuck | This DTC sets in continuous memory and on-demand if the ABS module detects the hydraulic pump motor is not rotating when it is commanded to run. |
| C052B:00 | ABS Pump Motor Control Range / Performance: No Sub Type Information | The SOBDMC sets this DTC when the ABS module sets DTC C0020:71. |
| C052C:00 | ABS Pump Motor Control Circuit / Open: No Sub Type Information | The SOBDMC sets this DTC when the ABS module sets DTC C0020:13. |
| C052D:00 | ABS Pump Motor Control Circuit High: No Sub Type Information | The SOBDMC sets this DTC when the ABS module sets DTC C0020:12. |
Possible Sources
- Fuse
- Wiring, terminals or connectors
- HCU
- ABS module
Visual Inspection and Diagnostic Pre-checks
- Make sure the vehicle battery terminals and cables are free of any corrosion and other contaminants.
- Make sure the vehicle battery terminals are tightened to their correct torque specifications.
- Make sure BJB fuse 7 (40A) and the fuse socket are OK.