Diagnostic Test

CHECK FOR AN ACTIVE DTC
1. Perform any Service Bulletins that may apply.
2. Turn the ignition on.
3. With the scan tool, read ABS DTCs and record on the repair order.
4. Cycle the ignition switch from off to on.
5. With the scan tool, read ABS DTCs.
  Is the DTC active?
  
  Yes
  - Go To 2
  No
  - The condition that caused the symptom is currently not present. Inspect the related wiring for a possible intermittent condition. Look for any chafed, pierced, pinched, or partially broken wires.
  - Perform the ABS-INTERMITTENT CONDITION TEST. Refer to ABS INTERMITTENT CONDITION .
VACUUM PRESSURE SIGNAL
1. Start the engine and let the vehicle run for five minutes.
2. With the scan tool, view and record the vacuum pressure signal with no brake applied.
3. Turn the engine off.
4. Ignition on.
5. With the scan tool, view and record the vacuum pressure with no brake applied.
  Is the vacuum pressure signal staying consistent?
  
  Yes
  - Go To 3
  No
  - Go To 5
MEASURE THE VACUUM PRESSURE SIGNAL
1. Start the engine.
2. Measure the vacuum pressure while pressing the brake pedal firmly several times.
  Does the vacuum drop below 14 mbar (2 psi)?
  
  Yes
  - Go To 4
  No
  - Perform the ABS-INTERMITTENT CONDITION TEST. Refer to ABS INTERMITTENT CONDITION .
CHECK FOR VACUUM PRESSURE SIGNAL CHANGE
1. Turn the ignition on.
2. Remove the Vacuum Pressure Sensor from the Booster.
3. Connect a vacuum pump to the Vacuum Pressure Sensor.
4. Apply vacuum to the Vacuum Pressure Sensor and watch for signal change.
  Is the vacuum pressure signal changing on the scan tool as vacuum is being applied?
  
  Yes
  - Go To 5
  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
  - Go To 6
  No
  - Replace the Brake Booster Check Valve.
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
CHECK BRAKE BOOSTER
1. Install the Brake Booster Check Valve.
2. Using a vacuum pump apply vacuum to the Brake Booster.
  Is the Brake Booster holding vacuum?
  
  Yes
  - Go To 7
  No
  - 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 .
VACUUM PRESSURE SENSOR
1. Replace the Vacuum Pressure Sensor.
2. Perform the ABS VERIFICATION TEST... ABS VERIFICATION TEST .
3. Turn the ignition on.
4. With the scan tool, read the DTCs.
  Did the DTC return?
  
  Yes
  - Go To 8
  No
  - Test complete.
CHECK RELATED HARNESS CONNECTIONS
1. Turn the ignition off.
2. Disconnect the ABS Module harness connector.
3. Disconnect all related in-line harness connections (if equipped).
4. Disconnect the related component harness connectors.
5. Inspect harness connectors, component connectors, and all male and female terminals for the following conditions:
  - Proper connector installation.
  - Damaged connector locks.
  - Corrosion.
  - Other signs of water intrusion.
  - Weather seal damage (if equipped).
  - Bent terminals.
  - Overheating due to a poor connection (terminal may be discolored due to excessive current draw).
  - Terminals that have been pushed back into the connector cavity.
  - Perform a terminal drag test on each connector terminal to verify proper terminal tension.
  Repair any conditions that are found.
6. Connect the ABS Module harness connector. Be certain that the harness connector is fully seated and the connector lock is fully engaged.
7. Connect all in-line harness connectors (if equipped). Be certain that all connectors are fully seated and the connector locks are fully engaged.
8. Connect the related component harness connectors. Be certain that all connectors are fully seated and the connector locks are fully engaged.
9. With the scan tool, erase DTCs.
  WARNING:
  To avoid possible serious or fatal injury, check brake capability is available before road testing.
10. Using the recorded Event and Environmental Data, along with the When Monitored and Set Conditions above, operate the vehicle in the conditions that set the DTC.
11. With the scan tool, read ABS Module DTCs.
  Did the DTC return?
  
  Yes
  - Replace the Anti-lock Brake System (ABS) Module in accordance with the Service Information. Refer to MODULE, ANTI-LOCK BRAKE SYSTEM (ABS), REMOVAL AND INSTALLATION .
  - Perform ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  No
  - The wiring or poor connection problem has been repaired.
  - Perform ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .