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Home >> Ford >> 2014 >> F-150 Limited, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 158 (Anti-Lock Brake System And Stability Control - F-150) >> Diagnosis And Testing >> Anti-Lock Control >> Pinpoint Tests >> Pinpoint Test U: The Brake Vacuum Pump Runs Continuously >> Pinpoint Test U: The Brake Vacuum Pump Runs Continuously

Pinpoint Test U: The Brake Vacuum Pump Runs Continuously

WARNING: This page is about a different car, the 2012 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
  1. U1 CHECK THE DTCs FROM THE ABS MODULE SELF-TEST 
    • Review the DTCs retrieved and recorded during Inspection and Verification.
    • Are DTCs C109D, C109E and C109F present? 
      • Yes  : DIAGNOSE any vacuum sensor DTCs first. GO to Pinpoint Test I .
      • No  : GO to U2.
  2. U2 CHECK THE BRAKE BOOSTER AND VACUUM HOSES FOR LEAKS 
    • Verify that all the vacuum hoses are connected to their ports.
    • Inspect the following items for leaks:
      • brake booster body
      • brake booster-to-master cylinder seal
      • brake booster-to-bulkhead seal
      • brake booster vacuum sensor seal
      • brake booster-to-vacuum pump hose
    • Are all hoses connected and are all items free of any leaks? 
      • Yes  : GO to U3.
      • No  : CONNECT and/or INSTALL new components as necessary. CLEAR the DTCs. REPEAT the self-test.
  3. U3 CHECK THE BRAKE BOOSTER VACUUM LEVEL (BBVACLVL) PID 
    • Ignition ON.
    • Enter the following diagnostic mode on the scan tool: DataLogger - ABS Module.
    • Start the engine.
    • Monitor the BBVACLVL PID while pressing and releasing the brake pedal.
    • Does the PID display change when the pedal is pressed? 
  4. U4 CHECK THE BRAKE VACUUM PUMP RELAY 
    • Ignition OFF.
    • Disconnect: Brake Vacuum Pump Relay.
    • Install a known good relay in place of the brake vacuum pump relay.
    • Ignition ON.
    • Does the brake vacuum pump run continuously? 
      • Yes  : REMOVE the known good relay. GO to U5.
      • No  : REMOVE the known good relay. INSTALL a new brake vacuum pump relay. CLEAR the DTCs. REPEAT the self-test.
  5. U5 CHECK THE RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND 
    • Disconnect: ABS Module C135.
    • Measure the resistance between the brake vacuum pump relay circuit CCB30 (GY/VT), harness side and ground.
      Fig 1: Measuring Resistance Between Brake Vacuum Pump Relay Circuit CCB30 (GY/VT), Harness Side And Ground
      G07958228Courtesy of FORD MOTOR CO.
    • Is the resistance greater than 10, 000 ohms? 
      • Yes  : GO to U6.
      • No  : REPAIR circuit CCB30 (GY/VT). CLEAR the DTCs. REPEAT the self-test.
  6. U6 CHECK THE VACUUM IN THE BRAKE BOOSTER 
    • Ignition OFF.
    • Connect: ABS Module C135.
    • Ignition ON.
    • Enter the following diagnostic mode on the scan tool: DataLogger - ABS Module.
    • NOTE: Subtract 3.3863 kPa (1 in-Hg) from the reading for every 304.8 m (1, 000 ft.) of elevation above sea level.
    • Monitor the BBVACLVL PID.
    • Is the brake vacuum reading higher than 71.11 kPa (21 in-Hg)? 
      • Yes  : GO to U7.
      • No  : The elevation in your area is causing the brake vacuum pump to run continuously. This is a normal condition.
  7. U7 CHECK FOR CORRECT ABS MODULE OPERATION 
    • Check ABS module C135 for:
      • corrosion
      • damaged pins
      • pushed-out pins
    • Connect: ABS Module C135.
    • Connect: Brake Vacuum Pump Relay.
    • Make sure each connectors seat correctly, then operate the system and verify the concern is still present.
    • Is the concern still present? 
      • Yes  : INSTALL a new ABS module. REFER to Anti-Lock Brake System (ABS) Module  . TEST the system for normal operation.
      • No  : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.
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