Diagnostic Test

VERIFY THE DTC IS ACTIVE
1. Turn the ignition on.
2. With the scan tool, read and record the DTCs.
3. With the scan tool, read and record Environmental Data to help identify the conditions in which the DTC was set.
4. With the scan tool, erase the DTCs.
5. Start the engine.
6. Press and release the brake pedal three times.
7. Wait five minutes or until red brake lamp illuminates.
8. With the scan tool, read and record the DTCs.
  Is the DTC Active at this time?
  
  Yes
  - Go To 2
  No
  - Check the vacuum supply line to brake booster for a pinched, cut, loose or cracked vacuum hose which could cause an intermittent condition.
  - Perform the ABS-INTERMITTENT CONDITION TEST. Refer to ABS INTERMITTENT CONDITION .
CHECK FOR PCM OR COMMUNICATION RELATED DTCS
1. Refer to the recorded DTCs.
  Are there any PCM or Communication related DTCs active?
  
  Yes
  - Perform the appropriate diagnostic procedures before continuing with this test. Refer to DTC INDEX (1 OF 2) and/or DTC INDEX (2 OF 2) .
  No
  - Go To 3
CHECK FOR OTHER ABS MODULE OR VACUUM RELATED DTCS
1. Refer to the recorded DTCs.
  Are there any ABS Module or Vacuum related DTCs active?
  
  Yes
  - Perform the appropriate diagnostic procedures before continuing with this test. Refer to DTC INDEX (1 OF 2) and/or DTC INDEX (2 OF 2) .
  No
  - Go To 4
CHECK VACUUM SUPPLY LINE
1. Turn the ignition off.
2. Check the vacuum supply line to brake booster for a pinched, cut, loose or open vacuum hose.
3. Disconnect the booster vacuum supply line and attach a vacuum pressure gauge.
4. Start the engine.
5. Raise the engine RPM above 600.
  Is the vacuum reading within this range 0 mbar (0 psi) to -135 mbar (2 psi)?
  
  Yes
  - Repair as necessary.
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  No
  - Go To 5
CHECK FOR VACUUM PRESSURE SIGNAL CHANGE
1. Turn the ignition on.
2. Remove the Vacuum Pressure Sensor from the Booster.
3. Block off the vacuum feed port.
4. Connect a vacuum pump to the Vacuum Pressure Sensor.
5. Apply vacuum to the Vacuum Pressure Sensor.
6. Using the scan tool, and a pressure gauge watch for the signal change.
7. Using the scan tool, watch for signal change.
  Is the signal changing and does it compare to the pressure gauge reading?
  
  Yes
  - Go To 6
  No
  - Replace the Vacuum Pressure Sensor.
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
CHECK BRAKE BOOSTER CHECK VALVE
1. Remove the Brake Booster Check Valve.
2. Apply vacuum to the booster side of the check valve.
  Is the Brake Booster Check Valve holding vacuum?
  
  Yes
  - Replace the Power Brake Booster in accordance with the Service Information. Refer to BOOSTER, POWER BRAKE, REMOVAL AND INSTALLATION .
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  No
  - Replace the Power Brake Booster Check Valve.
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .