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 Scan Tool Clear DTCs function |
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 to set. A seized pump motor, shorted pump motor windings or a poor power/ground at the 2-way EBCM connector can cause a DTC C0268 to set. Replace the EBCM or the BPMV if the following tests show that the pump motor EBCM internal circuits have failed.
Important: Reset the J 39200 test leads to zero prior to making any resistance measurements. Refer to the J 39200 in the user's manual.
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 J 39200. Reset the J 39200 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 |
