Visual Inspection and Diagnostic Pre-checks
- Make sure the power steering system is free from leaks and is operating correctly.
- Make sure the HydroMax unit is free from leaks.
NOTE:
Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may cause damage to the connector.
- CR1: CHECK THE ABS MODULE DTCS
- Ignition ON, engine OFF.
Carry out the ABS self-test.
- Is DTC C1050:9E present?
Yes No Go to CR2. If DTC C1050:9F is present, Go to CR3.
If DTC C1057:13 is present, Go to CR3.
For all other ABS module DTCs, No fault found.
GO to the ABS Module DTC Chart.
If the diagnostic scan tool cannot communicate with the ABS module, REFER to the Module Communications Network article.
For all others, No fault found. - CR2: CHECK THE FLOW SWITCH FOR A SHORT TO GROUND
- Ignition OFF.
- Hydraulic Fluid Flow Switch connector disconnected.
- HydroMax Relay connector disconnected.
- ABS Module connector disconnected.
- Measure the resistance between:
(+) Hydraulic Fluid Flow Switch Connector, Harness Side (-) HRC Ground - Is the resistance greater than 10, 000 ohms?
Yes No Go to CR6. REPAIR the circuit. - CR3: CHECK THE FLOW SWITCH CIRCUIT FOR AN OPEN
- Ignition OFF.
- Hydraulic Fluid Flow Switch connector disconnected. If not previously disconnected.
- HydroMax Relay connector disconnected. If not previously disconnected.
- ABS Module connector disconnected.
- Measure the resistance between:
(+) Hydraulic Fluid Flow Switch Connector, Harness Side (-) HydroMax Relay Connector, Harness Side HRC HRC - Measure the resistance between:
(+) Hydraulic Fluid Flow Switch Connector, Harness Side (-) ABS Module Connector, Harness Side HRC HRC - Are the resistances less than 3 ohms?
Yes No Go to CR4. REPAIR the circuit. - CR4: CHECK THE FLOW SWITCH GROUND CIRCUIT FOR AN OPEN
- Measure the resistance between:
(+) Hydraulic Fluid Flow Switch Connector, Harness Side (-) GND Ground - Is the resistance less than 3 ohms?
Yes No Go to CR5. REPAIR the circuit. - Measure the resistance between:
- CR5: CHECK THE FLOW SWITCH CIRCUIT FOR A SHORT TO VOLTAGE
- ABS Module connector disconnected. If not previously disconnected.
- Ignition ON, engine OFF.
- Measure the voltage between:
(+) Hydraulic Fluid Flow Switch Connector, Harness Side (-) HRC Ground - Is any voltage present?
Yes No REPAIR the circuit. Go to CR6. - CR6: CHECK THE HYDROMAX UNIT AND FLOW SWITCH OPERATION
- Ignition OFF.
- HydroMax Relay connector connected. Make sure the relay is fully seated.
- ABS Module connector connected. Make sure the connector seats and latches correctly.
- Start the engine.
- Measure the resistance between:
(+) Hydraulic Fluid Flow Switch Connector, Component Side (-) Hydraulic Fluid Flow Switch Connector, Component Side HRC GND - Ignition OFF.
- Measure the resistance between:
(+) Hydraulic Fluid Flow Switch Connector, Component Side (-) Hydraulic Fluid Flow Switch Connector, Component Side HRC GND - Is the resistance greater than 10, 000 ohms with the engine running and less than 3 ohms with the engine not running?
Yes No The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. INSPECT the HydroMax pump motor, HydroMax flow switch and ABS module electrical connectors and ADDRESS the root cause of any connector or pin issues: Go to CR7. - CR7: CHECK THE FLOW SWITCH CONTINUITY
- Remove the HydroMax flow switch.
- Measure the resistance between:
(+) Hydraulic Fluid Flow Switch Connector, Component Side (-) Hydraulic Fluid Flow Switch Connector, Component Side HRC GND - Is the resistance less than 3 ohms?
Yes No INSTALL a new HydroMax unit. REFER to the Power Brake Actuation article. INSTALL a new HydroMax flow switch.