C0021

C0021 - BRAKE BOOSTER PERFORMANCE






For a complete wiring diagram, refer to the Wiring Information.

- When Monitored:
With the ignition on.

- Set Condition:
When the Vacuum Pressure Sensor indicates a failure in the Vacuum Booster.






1. CHECK FOR A DTC C0021-BRAKE BOOSTER PERFORMANCE

NOTE: This DTC must be active for the results of this test to be valid.

1. Turn the ignition on.
2. With the scan tool, read and record DTCs.
3. With the scan tool, read and record Freeze Frame information.
4. With the scan tool, erase DTCs.
5. Start the engine.
6. Depress and release the brake pedal.
7. With the scan tool, read and record DTCs.

Does the scan tool display: C0021-BRAKE BOOSTER PERFORMANCE?

Yes
- Go To 2

No
- Perform the ABS Intermittent Condition diagnostic procedure.
- Refer to the ABS-INTERMITTENT CONDITION TEST.

2. CHECK FOR PINCHED VACUUM SUPPLY LINE

1. Turn the ignition off.
2. Check the vacuum supply line to brake booster for a pinched or kinked hose.

Were any problems found?

Yes
- Repair as necessary.
- Perform ABS VERIFICATION TEST.

No
- Go To 3

3. CHECK FOR VACUUM PRESSURE SIGNAL CHANGE

1. Turn the ignition off.
2. Connect a vacuum pump to the brake booster.
3. Apply vacuum to booster and watch for signal change.

Is the voltage signal changing on the scan tool as vacuum is being applied?

Yes
- Go To 4

No
- Replace the Vacuum Pressure Sensor in accordance with the Service Information.
- Perform ABS VERIFICATION TEST.

4. CHECK BRAKE BOOSTER

1. Check that the brake booster and check valve are operating properly.

Is the brake booster and check valve holding vacuum?

Yes
- Replace the Anti-Lock Brake Module in accordance with the Service Information.
- Perform ABS VERIFICATION TEST.

No
- Repair as necessary.
- Perform ABS VERIFICATION TEST.