C121E

C121E-BRAKE PRESSURE SENSOR COMPARATIVE PERFORMANCE

For a complete wiring diagram Refer to the Wiring Information.

- When Monitored:
With the ignition on.

- Set Condition:
When the Anti-Lock Brake Module indicates that the Brake Pressure Sensor Signal is irrational.





1. CHECK FOR A DTC C121E-BRAKE PRESSURE SENSOR COMPARATIVE PERFORMANCE
1.
2. Turn the ignition on.
3. With the scan tool, read and record DTCs.
4. With the scan tool, read and record Freeze Frame information.
5. With the scan tool, erase DTCs.
6. Start the engine.
7. Depress and release the brake pedal.
8. With the scan tool, read and record DTCs.

Does the scan tool display: C121E-BRAKE PRESSURE SENSOR COMPARATIVE PERFORMANCE?

Yes

- Go To 2

No

- Perform the ABS-INTERMITTENT CONDITION TEST. ABS Intermittent Condition Test.

2. CHECK BRAKE SWITCH
1. With the scan tool look at the Brake Switch Signal.
2. Apply the brakes on and off while checking for a Brake Switch Signal change.

Did the Brake Switch Signal change?

Yes

- Go To 3

No

- Repair as needed.

3. CHECK BRAKE PRESSURE SENSOR
1. With the scan tool look at Pressure Sensor Signal and the Brake Switch Signal.
2. With the brakes not applied the Pressure Sensor should read ± 15 bar (218 psi).
3. Apply the brakes hard, the Pressure Sensor should read above 15 bar (218 psi).

Did Brake Pressure Sensor increase above 15 bar (218 psi)?

Yes

- Replace the Integrated Control Unit.
- Perform ABS VERIFICATION TEST. ABS Verification Test.

No

- Go To 4

4. CHECK FOR AIR IN BRAKE SYSTEM

NOTE: Before continuing the brake system must be bled to verify there is no air in the brake system.

1. Turn ignition off.
2. Bleed brake system.

Was there any air in the brake system?

Yes

- Repair as needed.
- Perform ABS VERIFICATION TEST. ABS Verification Test.

No

- Replace the Integrated Control Unit.
- Perform ABS VERIFICATION TEST. ABS Verification Test.