Diagnostic Test

WARNING: This page is about a different car, the 2017 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

VACUUM PRESSURE SIGNAL
1. Start the engine.
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 2
  No
  - Go To 4
MEASURE THE VACUUM PRESSURE SIGNAL
1. Start the engine.
2. Measure the vacuum pressure while pressing the brake pedal several times.
3. Turn the engine off.
4. Ignition on.
  Does the vacuum drop below 14 mbar (2 psi)?
  
  Yes
  - Go To 3
  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 4
  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 5
  No
  - Replace the Brake Booster Check Valve.
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
CHECK BRAKE BOOSTER
1. Reinstall 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 6
  No
  - Replace the Power Brake Booster in accordance with the Service Information. Refer to BOOSTER, POWER BRAKE, REMOVAL .
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
EXTERNAL VACUUM PUMP
1. Verify the vehicle is equipped with a external vacuum pump.
  Is the vehicle equipped with a external vacuum pump?
  
  Yes
  - Repair or replace the External Vacuum Pump in accordance with the Service Information.
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  No
  - Go To 7
ANTI-LOCK BRAKE SYSTEM (ABS) MODULE
1. Turn the ignition off to the lock position.
2. Replace the Vacuum Pressure Sensor.
3. Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
4. With the scan tool, read the DTCs.
  Does the DTC remain active?
  
  Yes
  - Replace the Anti-Lock Brake System (ABS) Module in accordance with the Service Information. Refer to INTEGRATED CONTROL UNIT (ICU), REMOVAL .
  - Perform the ABS VERIFICATION TEST. Refer to ABS VERIFICATION TEST .
  No
  - Test complete, the condition or conditions that originally set this DTC are not present at this time.