Circuit Description
The EBCM applies the ground needed for pump motor activation. The low side of the pump motor has a feedback circuit to the EBCM. When the pump motor is commanded OFF and at rest, feedback voltage is high. When the pump motor is winding down after being commanded ON and then OFF, feedback voltage is low. The EBCM monitors this feedback voltage in order to determine if the motor is functioning properly.
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC C0267 Pump Motor Circuit Open |
| • | DTC C0268 Pump Motor Circuit Shorted |
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The vehicle speed is greater than 6 km/h (4 mph). |
Conditions for Setting the DTC
The EBCM detects any of the following conditions:
| • | An open or shorted pump motor |
| • | An open or shorted pump motor driver circuit |
| • | A seized pump motor |
Action Taken When the DTC Sets
If equipped, the following actions occur:
| • | The EBCM disables the ABS. |
| • | The ABS indicator turns ON. |
| • | The DIC displays the SERVICE BRAKE SYSTEM message. |
Conditions for Clearing the DTC
The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.
Diagnostic Aids
Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to the following:
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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It is imperative that the vehicle be driven to attempt to reset the DTC. Using the scan tool to perform a function test may not produce the same result, and therefore may cause misdiagnosis of the vehicle.
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This step tests if the electronic brake control module (EBCM) is capable of activating the ABS pump motor.
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A shorted ABS pump motor may damage the EBCM. It is imperative that the steps in the table be followed in order to prevent damage to a replacement EBCM.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
Does DTC C0267 set? | -- | Go to Step 6 | Go to Step 3 | |
3 | Does DTC C0268 set? | -- | Go to Step 4 | Go to Diagnostic Aids |
4 |
Caution: Unless directed otherwise, the ignition and start switch must be in the OFF or LOCK position, and all electrical loads must be OFF before servicing any electrical component. Disconnect the negative battery cable to prevent an electrical spark should a tool or equipment come in contact with an exposed electrical terminal. Failure to follow these precautions may result in personal injury and/or damage to the vehicle or its components. Does the resistance measure within the specified range? | 0.0-0.2 ohms | Go to Step 5 | Go to Step 10 |
5 | Use a DMM to measure the resistance of the ground circuit. Does the resistance measure within the specified range? | 0.0-0.2 ohms | Go to Step 7 | Go to Step 11 |
6 |
Important: On some applications, it may be necessary to separate the EBCM from the brake pressure modulator valve (BPMV) in order to perform this test. Also, DTC C0268 may set when this test is performed.
Does DTC C0267 set? | -- | Go to Step 12 | Go to Step 9 |
|
Important: On some applications, it may be necessary to separate the EBCM from the BPMV in order to perform this test. Also, DTC C0268 may set when this test is performed.
Does the test lamp illuminate and then turn OFF when the Function Test is performed? | -- | Go to Step 13 | Go to Step 8 | |
Use a DMM in order to measure the resistance across the ABS pump motor. Does the resistance measure within the specified range? | 0.3-1 ohms | Go to Step 12 | Go to Step 14 | |
9 | Inspect for poor connections at the pump motor pigtail connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 15 | Go to Step 13 |
10 | Repair the high resistance in the underhood electrical center or the battery positive voltage circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 15 | -- |
11 | Repair the high resistance in the ground circuit. Refer to Wiring Repairs . Did you complete the repair? | -- | Go to Step 15 | -- |
12 | Replace the EBCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 15 | -- |
13 | Replace the BPMV. Refer to Brake Pressure Modulator Valve Replacement . Did you complete the replacement? | -- | Go to Step 15 | -- |
14 |
Important: Following EBCM replacement, use the scan tool to perform the Tire Size Calibration procedure and the Trim Level Calibration procedure, if applicable. Replace the EBCM and the BPMV. Refer to Control Module References for replacement, setup, and programming and Brake Pressure Modulator Valve Replacement . Did you complete the replacements? | -- | Go to Step 15 | -- |
15 |
Does the DTC reset? | -- | Go to Step 3 | System OK |
