Circuit Description
The electronic brake control module (EBCM) monitors the HydroMax assist relay and the HydroMax motor for electrical continuity.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0272 Base Brake Pump Motor Circuit
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
| • | The EBCM detects open Hydromax assist relay contacts while the relay is energized. |
| • | The EBCM detects an open Hydromax pump motor or pump motor circuit. |
Action Taken When the DTC Sets
| • | The service brake soon indicator turns ON. |
| • | A fast rate audible chime turns ON. |
Conditions for Clearing the DTC
The conditions for setting the DTC are no longer present.
Diagnostic Aids
| • | Inspect the 10 A Hydromax fuse for an open. |
| • | Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to Testing for Electrical Intermittents , Testing for Intermittent Conditions and Poor Connections , Wiring Repairs and Connector Repairs . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Listen for an audible click when the brake pedal is pressed and released.
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This step tests whether or not the EBCM is able to energize the hydromax relay.
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This step tests for voltage supplied to the hydromax pump motor when the hydromax relay is energized.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Hydraulic Brake Schematics Connector End View Reference: Hydraulic Brake Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Does the DTC set? | Go to Step 3 | Go to Diagnostic Aids |
3 | Press the brake pedal. Does the hydromax pump motor run when the brake is applied? | Go to Step 14 | Go to Step 4 |
Press and release the brake pedal several times. Does the hydromax relay click each time the brake pedal is pressed and released? | Go to Step 7 | Go to Step 5 | |
Does the test lamp illuminate when the brake pedal is pressed? | Go to Step 12 | Go to Step 6 | |
6 |
Did you find and correct the condition? | Go to Step 17 | Go to Step 15 |
Does the test lamp illuminate when the brake pedal is pressed? | Go to Step 10 | Go to Step 8 | |
8 | Test the battery positive voltage circuit to the hydromax relay for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 17 | Go to Step 9 |
9 | Test the brake booster pump motor supply voltage circuit and the hydromax pump motor ground circuit for an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 17 | Go to Step 12 |
10 | Inspect for poor connections at the harness connector of the hydromax pump motor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 17 | Go to Step 11 |
11 | Replace the hydromax pump motor. Refer to Power Brake Booster Pump Replacement . Did you complete the replacement? | Go to Step 17 | -- |
12 | Inspect for poor connections at the harness connector of the hydromax relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 17 | Go to Step 13 |
13 | Replace the hydromax relay. Did you complete the replacement? | Go to Step 17 | -- |
14 | Turn the ignition off and test the hydromax motor feedback circuit for an open between terminal 10 of the EBCM connector and terminal A of the pump motor connector. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 17 | Go to Step 15 |
15 | Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 17 | Go to Step 16 |
16 | Replace the EBCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 17 | -- |
17 |
Does the DTC reset? | Go to Step 3 | System OK |
