Circuit Description
The pump motor circuit is integral to the BPMV. Battery voltage is constantly applied to the high side of the pump motor . The EBCM microprocessor switches an output driver transistor to supply the necessary ground for pump motor activation. The low side of the pump motor circuit also has a feedback circuit to the EBCM microprocessor. When the punp motor is not commanded on, the feedback circuit reports a high condition to the microprocessor, and when the pump motor is commanded on, the feedback line reports a low condition.
Conditions for Running the DTC
C0267
| • | Ignition switch in the RUN position. |
| • | The ABS bulb check is completed |
| • | Pump motor is off and has not been commanded on for the last 2 seconds. |
C0268
| • | Ignition switch in the RUN position. |
| • | The ABS bulb check is completed |
| • | Pump motor commanded ON at self test, or during ABS operation |
Conditions for Setting the DTC (C0267)
Low feedback voltage is present from the low side of the pump motor when the voltage is expected to be high: due to :
| • | Open motor winding. |
| • | Shorted pump motor driver transistor. |
| • | Open power circuit to pump motor. |
| • | Short to ground in the pump motor feedback circuit. |
Conditions for Setting the DTC (C0268)
High feedback voltage exists from the low side of the pump motor when the voltage is expected to be low due to:
| • | Siezed motor or pump. |
| • | Open pump motor driver transistor. |
| • | Short circuit in motor winding. |
| • | Short to voltage in the pump motor feedback circuit. |
Action Taken When the DTC Sets
| • | The ABS indicator lamp turns on |
| • | The ABS disables |
Malfunction responses to DTC C0267/C0268 vary, depending on the affected subsystem.
| • | ABS--Ignition latched |
| • | DRP--DRP non critical |
For a detailed explanation of DTC malfunction responses, refer to Self-Diagnostics
Conditions for Clearing the DTC
| • | Repair the conditions responsible for setting the DTC. |
| • | Use the Clear DTCs function on the Scan Tool |
Diagnostic Aids
The pump motor is integral with the BPMV. Do not service the pump motor separately. A poor power/ground connection at the 2-way EBCM connector or the 2-way motor harness from the EBCM to the pump motor can cause a DTC C0267. A seized pump motor, shorted pump motor windings or a poor power/ground at the 2-way EBCM connector can cause a DTC C0268. Replace the EBCM or the BPMV if the following tests show that the pump motor EBCM internal circuits have failed.
Important: Reset the DMM test leads to zero prior to making any resistance measurements. Refer to the DMM manual for instructions.
Test Description
The numbers below refer to the steps in the diagnostic table:
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check |
2 |
Is the connector and the wiring in good condition? | -- | Go to Step 3 | Go to Step 4 |
Measure the resistance between terminal A and terminal B of the 2-way pump motor pigtail connector using a DMM. Reset the DMM test leads to zero prior to making this resistance measurement. Does the resistance measure within the specified range? | 0.1-1.0ohms | Go to Step 5 | Go to Step 6 | |
4 | Repair the 2-way pump motor pigtail connector or wiring if necessary. Did you find and correct the condition? | -- | Go to Step 7 | -- |
5 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Did you complete the replacement? | -- | Go to Step 7 | -- |
6 | Replace the BPMV. Refer to Brake Pressure Modulator Valve Replacement . Did you complete the replacement? | -- | Go to Step 7 | -- |
7 | Operate the vehicle under the conditions for running the DTC as specified in the supporting text. Does the DTC set? | -- | Go to Step 2 | System OK |
