Normal Operation

Fused battery voltage for the Hydraulic Control Unit (HCU) pump motor is supplied to the ABS module by Battery Junction Box (BJB) fuse 96 (50A). The ABS module supplies the voltage and ground for the pump motor. The 2 components are hardwired together; there are no connectors or wiring harnesses between the 2 components.

When the ignition key is turned to the ON position, the ABS module commands the HCU pump on for 100 ms (±6 ms), then commands it off. After 6 ms, the ABS module reads the voltage that is being generated by the HCU pump.

• DTC C1095 (ABS Hydraulic Pump Motor Circuit Failure) - a continuous and on-demand DTC that sets if a short to voltage or ground is detected, if a locked up pump motor is detected or if there is an internal failure of the ABS module. 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 C1095 sets.
• DTC C1096 (ABS Hydraulic Pump Motor Circuit Open) - a continuous and on-demand DTC that sets if an open circuit is detected. The pump motor is checked for an open circuit 2 seconds after the most recent successful pump motor off command. The ABS module sends a reference voltage to the pump motor and looks for a voltage drop. If voltage feedback remains greater than 0.75 volt for more than 50 ms (±6 ms) after these conditions have been met, DTC C1096 sets.

This pinpoint test is intended to diagnose the following: 

• Wiring, terminals or connectors
• Hydraulic pump motor
• ABS module