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C0267 & C0268 Pump Motor Circuit Open DTC's

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Old 07-24-2006, 07:25 PM   #1
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C0267 - Pump Motor Circuit Open
C0268 - Pump Motor Circuit Shorted

310 & 325 ABS
Circuit Description
The EBCM internal relay supplies battery voltage to the pump motor. The EBCM applies the ground needed for pump motor activation. The low side of the pump motor has a feedback circuit to the EBCM microprocessor. When the pump motor is commanded off, feedback voltage is high. When the pump motor is winding down after being commanded on and then off, feedback voltage is low due to the back-EMF generated in the motor windings as the rotor turns. The feedback voltage then rises correspondingly as the rotor slows to a stop and the back-EMF diminishes.

Conditions for Running the DTC

* The ignition is ON.
* The IPC bulb check is complete.
* The vehicle is moving at a speed greater than 5 km/h (3 mph).

Conditions for Setting the DTC
The EBCM detects low feedback voltage from the pump motor 2 seconds after the pump motor is commanded off.

The EBCM detects high feedback voltage from the pump motor 5 milliseconds after the pump motor is commanded off.

Action Taken When the DTC Sets

* The ABS indicator is commanded on.
* The ABS is disabled for the remainder of the ignition cycle.

Conditions for Clearing the DTC

* Repair the condition(s) responsible for setting the DTC.
* Use a scan tool in order to clear the DTC.

Diagnostic Aids
Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to Testing for Intermittent and Poor Connections, Connector Repairs and Wiring Repairs in Wiring Systems.

Test Description

The number below refers to the step number on the diagnostic table.

3. Separate the EBCM from the BPMV in order to access the pump motor pigtail connector. Refer to Electronic Brake Control Module (EBCM) Replacement (310 ABS) or Electronic Brake Control Module (EBCM) Replacement (325 ABS). This step tests if the EBCM is capable of activating the pump motor. Replace the EBCM if DTC C0267 sets while the ABS motor test is performed. DTC C0268 may set while this test is performed even if the EBCM is functioning properly.


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