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Home >> Ford >> 2016 >> Fusion Titanium, AWD >> Repair and Diagnosis (Single Page) >> Brakes >> Anti-Lock Brakes >> Anti-Lock Brake System Component Testing (Except Hybrid) >> Pinpoint Tests >> Pinpoint Tests U: The Brake Booster Vacuum Pump Is Inoperative >> Normal Operation and Fault Conditions

Normal Operation and Fault Conditions

Through the use of the brake booster vacuum sensor, the ABS module monitors the vacuum in the brake booster. When the vacuum reaches the low side of a predetermined threshold, the ABS module provides a ground for the vacuum pump relay coil to activate the brake vacuum pump. Once the vacuum in the brake booster reaches the high side of a predetermined threshold, the ABS module removes the ground connection for the vacuum pump relay coil, deactivating the brake vacuum pump. 

A leak in the brake booster vacuum system, an inoperative relay, an inoperative pump, a short to ground, a short to voltage or an open in the vacuum pump relay or vacuum pump motor circuits can cause the ABS module to set one or more DTCs.

Possible Causes 

Visual Inspection and Diagnostic Pre-checks 

Fig 1: Antilock Braking System (ABS) Module Connector - C135
G11681758Courtesy of FORD MOTOR CO.
CONNECTOR PIN REFERENCE (HARNESS SIDE)

Circuit Pin

Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may cause damage to the connector.

  1. U1: CHECK FOR DTC C0047:16, C0047:1C, C0047:1E OR C0047:64 
    • Ignition ON, engine OFF.
    • Carry out the ABS self-test.
    • Is DTC C0047:16, C0047:1C, C0047:1E or C0047:64 present? 
      Yes No
      DIAGNOSE these DTCs first.
      Go to PINPOINT TEST C .      		 Go to  U2.
  2. U2: CHECK THE BRAKE VACUUM PUMP RELAY 
    • Ignition OFF.
    • Remove the brake vacuum pump relay from the BJB.
    • Substitute a known good relay.
    • Apply the brake pedal several times to relieve the vacuum.
      NOTE: Have an assistant listen for the vacuum pump to activate when the ignition is cycled ON.
    • Ignition ON, engine OFF.
    • Does the vacuum pump run when the ignition is cycled ON? 
      Yes No
      REMOVE the known good relay. INSTALL a new brake vacuum pump relay. REMOVE the known good relay.
      Go to  U3.
  3. U3: CHECK FOR DTC P258A:14 
    • Review the results from the ABS module self-test.
    • Is DTC P258A:14 present? 
      Yes No
      Go to  U5. Go to  U4.
  4. U4: CHECK THE BRAKE VACUUM PUMP RELAY CONTROL CIRCUIT FOR A SHORT TO VOLTAGE 
    • Measure the voltage between:
      (+) Vacuum Pump Relay Connector, Harness Side (-)
      VPRC Ground
    • Is any voltage present? 
      Yes No
      REPAIR the circuit. Go to  U5.
  5. U5: CHECK THE BRAKE VACUUM PUMP RELAY CONTROL CIRCUIT FOR AN OPEN 
    • Ignition OFF.
    • ABS Module connector disconnected. (C135)
    • Measure the resistance between:
      (+) Vacuum Pump Relay Connector, Harness Side (-) ABS Module (C135) Connector, Harness Side
      VPRC VPRC
    • Is the resistance less than 3 ohms? 
      Yes No
      Go to  U6. REPAIR the circuit.
  6. U6: CHECK THE BRAKE VACUUM PUMP RELAY OUTPUT CIRCUIT FOR AN OPEN 
    • Vacuum Pump Motor connector disconnected.
    • Measure the resistance between:
      (+) Vacuum Pump Relay Connector, Harness Side (-) Vacuum Pump Motor Connector, Harness Side
      VPRO VPRO
    • Is the resistance less than 3 ohms? 
      Yes No
      Go to  U7. REPAIR the circuit.
  7. U7: CHECK THE BRAKE VACUUM PUMP RELAY OUTPUT CIRCUIT FOR A SHORT TO GROUND 
    • Measure the resistance between:
      (+) Vacuum Pump Motor Connector, Harness Side (-)
      VPRO Ground
    • Is the resistance greater than 10, 000 ohms? 
      Yes No
      Go to  U8. REPAIR the circuit.
  8. U8: CHECK THE BRAKE VACUUM PUMP GROUND CIRCUIT FOR AN OPEN 
    • Measure the resistance between:
      (+) Vacuum Pump Motor Connector, Harness Side (-)
      GND Ground
    • Is the resistance less than 3 ohms? 
      Yes No
      Go to  U9. VERIFY ground eyelet G304 is clean and securely fastened. CLEAN or TIGHTEN as necessary. If G304 is OK, REPAIR the circuit.
  9. U9: CHECK THE BRAKE VACUUM PUMP RELAY SWITCHED VOLTAGE SUPPLY CIRCUIT FOR AN OPEN 
    • Measure the voltage between:
      (+) Vacuum Pump Relay Connector, Harness Side (-)
      B+ Ground
    • Is the voltage greater than 11 volts? 
      Yes No
      Go to  U10. REPAIR the circuit.
  10. U10: CHECK THE BRAKE VACUUM PUMP RELAY COIL VOLTAGE SUPPLY CIRCUIT FOR AN OPEN 
    • Ignition ON, engine OFF.
    • Measure the voltage between:
      (+) Vacuum Pump Relay Connector, Harness Side (-)
      IGN START/RUN Ground
    • Is the voltage greater than 11 volts? 
      Yes No
      Go to  U11. REPAIR the circuit.
  11. U11: CHECK THE BRAKE VACUUM PUMP OPERATION 
    • Ignition OFF.
    • Vacuum Pump Motor connector connected.
      NOTE: It may be necessary to use a higher amperage fuse to activate the vacuum pump.
    • Connect a 5 amp fused jumper wire between the following:
      Point A Vacuum Pump Relay Connector, Component Side Point B Vacuum Pump Relay Connector, Component Side
      B+ VPRO
    • Remove the fused jumper wire.
    • Does the brake vacuum pump run when the fused jumper wire is connected? 
      Yes No
      Go to  U12. INSTALL a new brake vacuum pump. REFER to the Removal and Installation procedure in Anti-Lock Brake System (ABS) And Stability Control (Except Hybrid) .
  12. U12: CHECK FOR CORRECT ABS MODULE OPERATION 
    • Ignition OFF.
    • Disconnect and inspect the ABS module connector (if not previously disconnected).
    • Repair:
      • corrosion (install new connector or terminal - clean module pins)
      • damaged or bent pins - install new terminals or pins
      • pushed-out pins - install new pins as necessary
    • Reconnect the ABS module connector. Make sure it seats and latches correctly.
    • Operate the system and determine if the concern is still present.
    • Is the concern still present? 
      Yes No
      INSTALL a new ABS module.
      CHECK OASIS for any applicable Technical Service Bulletins TSBs.
      If a TSB exists for this concern, DISCONTINUE this test and FOLLOW the TSB instructions.
      If no TSBs address this concern, INSTALL a new ABS module. REFER to Anti-Lock Brake System (ABS) And Stability Control (Except Hybrid) .
      ORDER a replacement ABS module and INCLUDE the RVC on the form.
      If this is a Ford paid repair, INCLUDE the RVC on the warranty claim form.
      When complete, SELECT the "X" in the top right corner to CLOSE this procedure.      		 The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.
      If this is a Ford paid repair, INCLUDE the RVC on the warranty claim form.
      When complete, SELECT the "X" in the top right corner to CLOSE this procedure.
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