Circuit Description
The EBCM internal relay supplies power to all six solenoid coils (three isolation solenoid coils and three dump solenoid coils) and the pump motor when the ABS is required. The relay and the six solenoid coils are located within the EBCM.
Conditions for Running the DTC
| • | Ignition switch in the RUN position. |
| • | The EBCM internal relay is commanded ON. |
Conditions for Setting the DTC (C0265)
| • | The EBCM microprocessor commands the relay on |
| • | Low voltage exists on all six solenoid driver circuits when high voltage is expected (the solenoid is not energized) |
Conditions for Setting the DTC (C0266)
| • | The ABS bulb check is complete |
| • | High voltage exists on the pump motor driver circuit when all are expected to be low (the relay is not commanded on) |
Action Taken When the DTC Sets
| • | The ABS indicator lamp turns on |
| • | The ABS disables |
Malfunction responses to DTC C0265/66 vary, depending on the affected subsystem.
| • | ABS--Ignition latched |
| • | DRP--DRP critical (except for DTC C0266 which is 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 (DTC C0265)
DTC C0265 usually sets because of an open relay coil or non-closable relay contacts. The relay is located within the EBCM. The relay is not serviceable. If the test does not repair the DTC, then replace the EBCM.
If DTC C0265 appears with other DTCs repair the other DTCs first. Clear all DTCs. Then run three function tests with the Scan Tool. Refer to this diagnostic chart if DTC C0265 resets.
Diagnostic Aids (DTC C0266)
DTC C0266 usually sets when the relay contacts are stuck closed. The relay is located within the EBCM. The relay is not serviceable. If the test does not repair the DTC, then replace the EBCM.
Test Description
The numbers below refer to the steps in the diagnostic table:
-
This step determines the battery voltage available to the EBCM.
-
This step verifies that the motor and solenoid power circuit is OK.
-
This step determines if the ignition 3 power and signal ground circuits are OK, then attempts to determine if the DTC will set again during a road test.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the ABS Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check | ||||||||
Is the connector in good condition? | -- | Go to Step 3 | Go to Step 6 | |||||||||
Connect the a test lamp between the motor and solenoid power circuit and a good ground. Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 5 | |||||||||
Does the DTC set? | -- | Go to Step 7 | Go to Diagnostic Aids | |||||||||
5 | Test the motor and solenoid power circuit for an open/high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 8 | -- | ||||||||
6 | Repair the 2-way EBCM harness connector. Refer to Connector Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 8 | -- | ||||||||
7 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Did you complete the replacement? | -- | Go to Step 8 | -- | ||||||||
8 | 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 |
