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Home >> Mercury >> 2008 >> Milan Base, 3.0 1, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 52 (Four-Wheel Drive Systems (ESOF) - F250-F550 Super Duty) >> Diagnosis And Testing >> Four-Wheel Drive Systems - Electronic Shift >> Pinpoint Tests - Electronic Shift >> Pinpoint Test G: The Front Axle Does Not Engage Correctly

Pinpoint Test G: The Front Axle Does Not Engage Correctly

WARNING: This page is about a different car, the 2005 Ford Pickup, 2005 Ford F550 Super Duty, 2005 Ford F450 Super Duty, and 2005 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
  1. G1 RETRIEVE THE DIAGNOSTIC TROUBLE CODES (DTCs) 
    • Refer to the recorded results of the 4WD control module self-test.
    • Were any DTCs retrieved? 
    • Yes  : If DTC P1832, GO to G2.

      If DTC P1834, GO to  G3.

      If DTC P1876, GO to  G4.

      If DTC P1877, GO to  G3.

    • No  : GO to  G8.
  2. G2 CHECK FOR VOLTAGE TO THE PULSE VACUUM HUBLOCK (PVH) SOLENOID 
    • Disconnect: PVH Solenoid C1247.
    • Key in ON position.
    • Measure the voltage between PVH solenoid C1247, circuit 295 (LB/PK), harness side and ground.
      Fig 1: Checking Voltage To Pulse Vacuum Hublock (PVH) Solenoid
      G03909584Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
    • Yes  : GO to G3.
    • No  : REPAIR circuit 295 (LB/BK). CLEAR the DTCs. REPEAT the self-test.
  3. G3 CHECK CIRCUITS 605 (RD) AND 145 (GY/BK) FOR A SHORT TO VOLTAGE 
    • Measure the voltage between PVH solenoid C1247, circuit 605 (RD), harness side and ground; and between PVH solenoid C1247, circuit 145 (GY/BK), harness side and ground.
      Fig 2: Checking Circuits 605 (RD) And 145 (GY/BK) For Short To Voltage
      G03909585Courtesy of FORD MOTOR CO.
    • Is any voltage present? 
    • Yes  : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
    • No  : GO to G4.
  4. G4 CHECK CIRCUITS 605 (RD) AND 145 (GY/BK) FOR A SHORT TO GROUND 
    • Measure the resistance between PVH solenoid C1247, circuit 605 (RD), harness side and ground; and between PVH solenoid C1247, circuit 145 (GY/BK), harness side and ground.
      Fig 3: Checking Circuits 605 (RD) And 145 (GY/BK) For Short To Ground
      G03909586Courtesy of FORD MOTOR CO.
    • Are the resistances greater than 10,000 ohms? 
    • Yes  : GO to G5.
    • No  : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
  5. G5 CHECK CIRCUITS 605 (RD) AND 145 (GY/BK) FOR AN OPEN 
    • Disconnect: 4WD Control Module C281b.
    • Measure the resistance between 4WD control module C281b pin 7, circuit 605 (RD), harness side and PVH solenoid C1247, circuit 605 (RD), harness side.
      Fig 4: Checking Circuits 605 (RD) And 145 (GY/BK) For Open (1 Of 2)
      G03909587Courtesy of FORD MOTOR CO.
    • Measure the resistance between 4WD control module C281b pin 1, circuit 145 (GY/BK), harness side and PVH solenoid C1247, circuit 145 (GY/BK), harness side.
      Fig 5: Checking Circuits 605 (RD) And 145 (GY/BK) For Open (2 Of 2)
      G03909588Courtesy of FORD MOTOR CO.
    • Are the resistances less than 5 ohms? 
    • Yes  : GO to G6.
    • No  : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
  6. G6 CHECK THE PVH SOLENOID COILS 
    • Measure the resistance between the PVH solenoid terminal 1 and terminal 2; and measure the resistance between PVH solenoid terminal 2 and terminal 3.
      Fig 6: Checking PVH Solenoid Coils
      G03909589Courtesy of FORD MOTOR CO.
    • Are the resistances between 45 and 55 ohms? 
  7. G7 CHECK FOR CORRECT MODULE OPERATION 
    • Check for:
      • corrosion
      • pushed-out pins
    • Connect any disconnected connectors making sure they are seated correctly.
    • Make sure all other system connectors are fully seated.
    • Operate the system and verify the concern is still present.
    • Is the concern still present? 
    • Yes  : INSTALL a new 4WD control module. REFER to FOUR-WHEEL DRIVE (4WD) CONTROL MODULE  in this section. CLEAR the DTCs. REPEAT the self-test.
    • No  : The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.
  8. G8 CHECK ENGAGE VACUUM SUPPLY TO THE RIGHT KNUCKLE 
    NOTE: The remaining steps require the use of a calibrated vacuum gauge that is accurate to within a minimum of 0.1 in-Hg. It is recommended the Pressure Vacuum Module 105-R0099 or equivalent be used.
    • Make sure hublocks are in the AUTO position.
    • Lift and support the vehicle off the ground until the front tires can be spun freely. Refer to JACKING AND LIFTING .
      • NOTE: The engine is required to be at idle during the following steps to supply the vacuum required for the hublocks to engage and disengage.
    • Start the engine and allow to idle.
    • Turn the MSS to the 2WD position and wait 15 seconds. If switching from 4x4 mode, wait an additional 45 seconds.
    • Disconnect the vacuum line at the right front knuckle and install a vacuum gauge on the line.
      Fig 7: Installing Vacuum Gauge To Vacuum Line
      G03909590Courtesy of FORD MOTOR CO.
    • Disconnect the vacuum line at the left front knuckle and plug the line.
      Fig 8: Disconnecting Vacuum Line At Left Front Knuckle And Plugging Line
      G03909591Courtesy of FORD MOTOR CO.
    • Turn the MSS to 4x4.
      • NOTE: Normal operation applies engagement vacuum for 45 seconds and then drops to 0 in-Hg.
    • Observe the vacuum reading within 45 seconds.
    • Is the vacuum reading greater than 10 in-Hg? 
    • Yes  : GO to G9.
    • No  : GO to  G16.
  9. G9 CHECK DISENGAGE VACUUM SUPPLY TO THE RIGHT KNUCKLE 
    • Turn the MSS to 2WD.
      • NOTE: Normal operation applies regulated disengagement vacuum for 15 seconds and then drops to 0 in-Hg.
    • Observe the vacuum reading for 15 seconds.
    • Is the vacuum reading between 5.8 and 7.3 in-Hg? 
    • Yes  : GO to G10.
    • No  : GO to  G18.
  10. G10 CHECK FOR MECHANICAL ENGAGEMENT AT THE RIGHT FRONT AXLE 
    • Remove the vacuum gauge and connect the vacuum line at the right front knuckle.
    • Turn the MSS to 4x4.
    • Wait one minute.
    • Rotate the right front tire one revolution forward and one revolution backward while observing the right front axle shaft and universal joint.
    • Did the right front axle shaft and universal joint turn? 
    • Yes  : GO to G11.
    • No  : GO to G11.
  11. G11 CHECK FOR MECHANICAL DISENGAGEMENT AT THE RIGHT FRONT AXLE 
    • Turn the MSS to 2WD.
    • Wait one minute.
    • Rotate the right front tire one revolution forward and one revolution backward, while observing the right front axle shaft and universal joint.
    • Did the right front axle shaft and universal joint turn? 
    • Yes  : GO to  G19.
    • No  : GO to G12.
  12. G12 CHECK ENGAGE VACUUM SUPPLY TO THE LEFT KNUCKLE 
    • Remove the plug from the vacuum line at the left front knuckle and install the vacuum gauge on the line.
      Fig 9: Removing Plug From Vacuum Line At Left Front Knuckle And Installing Vacuum Gauge
      G03909590Courtesy of FORD MOTOR CO.
    • Disconnect the vacuum line at the right front knuckle and plug the line.
      Fig 10: Disconnecting Vacuum Line At Right Front Knuckle And Plugging Line
      G03909591Courtesy of FORD MOTOR CO.
    • Turn the MSS to 4x4.
      • NOTE: Normal operation applies engagement vacuum for 45 seconds and then drops to 0 in-Hg.
    • Observe the vacuum reading for 45 seconds.
    • Is the vacuum reading greater than 10 in-Hg? 
    • Yes  : GO to G13.
    • No  : CHECK the vacuum harness for damage or an obstruction. REPAIR as necessary. TEST the system for normal operation.
  13. G13 CHECK DISENGAGE VACUUM SUPPLY TO THE LEFT KNUCKLE 
    • Turn the MSS to 2WD.
      • NOTE: Normal operation applies regulated disengagement vacuum for 15 seconds and then drops to 0 in-Hg.
    • Observe the vacuum reading within 15 seconds.
    • Is the vacuum reading between 5.8 and 7.3 in-Hg? 
    • Yes  : GO to G14.
    • No  : CHECK the vacuum harness for damage or an obstruction. REPAIR as necessary. TEST the system for normal operation.
  14. G14 CHECK FOR MECHANICAL ENGAGEMENT AT THE LEFT FRONT AXLE 
    • Remove the vacuum gauge and connect the vacuum line at the left front knuckle.
    • Turn the MSS to 4x4.
    • Wait one minute.
    • Rotate the left front tire one revolution forward and one revolution backward while observing the left front axle shaft and universal joint.
    • Did the left front axle shaft and universal joint turn? 
    • Yes  : GO G15.
    • No  : GO to  G19.
  15. G15 CHECK FOR MECHANICAL DISENGAGEMENT AT THE LEFT FRONT AXLE 
    • Turn the MSS to 2WD.
    • Wait one minute.
    • Rotate the left front tire one revolution forward and one revolution backward while observing the left front axle shaft and universal joint.
    • Did the left front axle shaft and universal joint turn? 
    • Yes  : GO to  G19.
    • No  : GO to  G18.
  16. G16 CHECK THE MANIFOLD VACUUM SUPPLY 
    • Make sure the engine is still at idle.
    • Disconnect the vacuum harness from the PVH solenoid.
      Fig 11: Disconnecting Vacuum Harness From PVH Solenoid
      G03909594Courtesy of FORD MOTOR CO.
    • Connect a vacuum gauge to the reservoir output line at the PVH solenoid connection.
      Fig 12: Connecting Vacuum Gauge To Reservoir Output Line At PVH Solenoid Connection
      G03909595Courtesy of FORD MOTOR CO.
    • Is the vacuum reading greater than 10 in-Hg? 
    • Yes  : GO to G17.
    • No  : For gasoline engines, REPAIR the vacuum leak. TEST the system for normal operation.

      For diesel engines, GO to  G27.

  17. G17 CHECK THE PVH SOLENOID OUTPUT IN 2WD 
    • Connect the vacuum harness to the PVH solenoid so only the reservoir output line is connected to the solenoid.
      Fig 13: Connecting Vacuum Harness To PVH Solenoid
      G03909596Courtesy of FORD MOTOR CO.
    • Connect a vacuum gauge to the PVH solenoid output port.
      Fig 14: Connecting Vacuum Gauge To PVH Solenoid Output Port
      G03909597Courtesy of FORD MOTOR CO.
      • NOTE: Normal operation applies engagement vacuum for 45 seconds and then drops to 0 in-Hg.
    • Turn the MSS to 4x4 and wait 45 seconds.
      • NOTE: Normal operation applies regulated disengagement vacuum for 15 seconds and then drops to 0 in-Hg.
    • Turn the MSS to 2WD while observing the vacuum gauge.
    • Is the vacuum reading between 5.8 and 7.3 in-Hg? 
  18. G18 CHECK THE PVH SOLENOID OUTPUT IN 4x4 
      NOTE: Normal operation applies engagement vacuum for 45 seconds and then drops to 0 in-Hg.
    • Turn the MSS to 4x4 and observe the vacuum reading for 45 seconds.
    • Is the vacuum reading greater than 10 in-Hg in 4x4? 
    • Yes  : CHECK the vacuum harness for leaks, restrictions, kinks or melted lines. REPAIR the vacuum harness as necessary. TEST the system for normal operation.
    • No  : INSTALL a new PVH solenoid. REFER to PULSE VACUUM HUBLOCK (PVH) SOLENOID  in this section. TEST the system for normal operation.
  19. G19 CHECK FOR A STATIC VACUUM LEAK 
    • Key in OFF position.
    • Disconnect the vacuum line at the knuckle.
    • Connect a vacuum pump to the knuckle fitting and T in the vacuum gauge between the knuckle and the pump.
      Fig 15: Connecting A Vacuum Pump To Knuckle Fitting And T In Vacuum Gauge Between Knuckle And Pump
      G03909598Courtesy of FORD MOTOR CO.
    • Pump until 20 in-Hg is read.
    • Observe the vacuum reading for 30 seconds.
    • Is the vacuum drop less than 0.5 in-Hg in 30 seconds? 
    • Yes  : GO to G20.
    • No  : GO to  G21.
  20. G20 CHECK FOR DYNAMIC VACUUM LEAK 
    • Make sure the vacuum is still at 20 in-Hg.
    • Rotate the front tire for 30 seconds while observing vacuum reading.
    • Is the vacuum drop less than 0.5 in-Hg in 30 seconds? 
    • Yes  : GO to  G22.
    • No  : GO to  G24.
  21. G21 CHECK FOR A LOOSE KNUCKLE FITTING 
    • Remove the vacuum pump and gauge line from the knuckle.
    • Make sure the knuckle fitting is tightened to 20 Nm (15 lb-ft).
    • Install the vacuum pump and gauge line on the knuckle and pump to 20 in-Hg.
      Fig 16: Installing Vacuum Pump And Gauge Line On Knuckle
      G03909598Courtesy of FORD MOTOR CO.
    • Observe the vacuum reading for 30 seconds.
    • Is the vacuum drop less than 0.5 in-Hg in 30 seconds? 
    • Yes  : GO to G22.
    • No  : INSTALL a new hublock. REFER to HUBLOCK  in this section. TEST the system for normal operation.
  22. G22 CHECK FOR A HUBLOCK LEAK 
    • Remove the hublock. REFER to HUBLOCK  in this section.
    • Remove and discard the hublock O-ring.
    • Install a new hublock O-ring.
    • Rotate the hublock to the AUTO position.
    • Install the hublock into the special tool. Be sure that the hublock is completely seated into the special tool.
      Fig 17: Checking Hublock Leak
      G03923792Courtesy of FORD MOTOR CO.
    • Connect the vacuum pump and pump to 20 in-Hg. Release the vacuum pressure, then remove the hublock. The hublock should be in the engaged position. The inner drive gear will not rotate. Reinstall the hublock into the special tool. Pump to 5.8-7.8 in-Hg.
    • Release the vacuum pressure, then remove the hublock. The hublock should be in the disengaged position. The inner drive gear will rotate freely.
    • Did the hublock engage and disengage correctly? 
    • Yes  : GO to G23.
    • No  : INSTALL a new hublock. REFER to HUBLOCK  in this section. TEST the system for normal operation.
  23. G23 CHECK THE HUBLOCK SEAL 
      NOTE: Install a new O-ring on the special tool. The O-ring used is the same as the hublock. Apply a light film of lubricant on the O-ring.
      NOTE: Using emery cloth, clean the sealing surface of the wheel hub before testing.
      Fig 18: Installing Special Tool And Retainer Ring
      G03923793Courtesy of FORD MOTOR CO.
    • Install the special tool and the retainer ring. Make sure the retainer ring is seated in the groove.
    • Connect the vacuum pump and pump to 20 in-Hg. Observe the vacuum reading for 30 seconds.
      Fig 19: Connecting Vacuum Pump
      G03909605Courtesy of FORD MOTOR CO.
    • Is the vacuum drop less than 0.5 in-Hg in 30 seconds? 
    • Yes  : The old hublock seal was worn or damaged. REMOVE the special tool. INSTALL the hublock with a new O-ring. TEST the system for normal operation.
    • No  : GO to G24.
  24. G24 CHECK THE KNUCKLE SEAL 
    • Remove the wheel hub assembly. Refer to FRONT SUSPENSION - 4X4 .
      • NOTE: Install a new O-ring on the special tool. The O-ring used is the same as the wheel hub. Apply a light film of lubricant on the O-ring.
      NOTE: Using emery cloth, clean the sealing surface of the wheel hub before testing.
      Fig 20: Installing Special Tool
      G03923795Courtesy of FORD MOTOR CO.
    • Install the special tool.
    • Connect the vacuum pump and pump to 20 in-Hg. If checking for a dynamic leak, carefully rotate the U-joint while observing the vacuum reading for 30 seconds.
    • Is the vacuum drop less than 0.5 in-Hg in 30 seconds? 
    • Yes  : GO to G25.
    • No  : INSTALL a new knuckle seal. REFER to FRONT SUSPENSION - 4X4 . RESTORE the system to normal condition. TEST the system for normal operation.
  25. G25 CHECK THE WHEEL HUB ASSEMBLY 
    • Remove and discard the wheel hub O-ring.
      • NOTE: Apply a light film of lubricant on the tool O-ring.
      NOTE: Do not remove the ABS sensor.
      Fig 21: Installing Special Tool And Retainer Ring
      G03923793Courtesy of FORD MOTOR CO.
    • Install the special tool and the retainer ring. Make sure the retainer ring is seated in the groove.
    • Install a new O-ring on the wheel hub.
    • Install the special tool. Make sure the tool is seated over the wheel hub seal.
    • Install the special tool. Make sure the tool is seated over the wheel hub seal.
      Fig 22: Installing Special Tool
      G03923797Courtesy of FORD MOTOR CO.
    • Connect the vacuum pump and pump to 20 in-Hg. If checking for a dynamic leak, carefully rotate the hubflange relative to the wheel bearing flange while observing the vacuum reading for 30 seconds.
      Fig 23: Checking Wheel Hub Assembly Dynamic Leak
      G03909610Courtesy of FORD MOTOR CO.
    • Is the vacuum drop less than 0.5 in-Hg in 30 seconds? 
    • Yes  : The old wheel hub O-ring was worn or damaged. REMOVE the special tools. RESTORE the system to normal condition. TEST the system for normal operation.
    • No  : GO to G26.
  26. G26 CHECK THE WHEEL HUB ASSEMBLY 
    • Remove the ABS sensor.
    • Install the special tool.
      Fig 24: Installing Special Tool
      G03923799Courtesy of FORD MOTOR CO.
    • Connect the vacuum pump and pump to 20 in-Hg. Observe the vacuum reading for 30 seconds.
      Fig 25: Checking Wheel Hub Assembly
      G03909612Courtesy of FORD MOTOR CO.
    • Is the vacuum drop less than 0.5 in-Hg in 30 seconds? 
    • Yes  : INSTALL a new ABS sensor. REMOVE the special tools. RESTORE the system to normal condition. TEST the system for normal operation.
    • No  : INSTALL a new wheel hub assembly. REFER to FRONT SUSPENSION - 4X4 . TEST the system for normal operation.
  27. G27 CHECK THE VOLTAGE AT THE VACUUM PUMP 
    • Key in OFF position.
    • Disconnect: Vacuum Pump C1119.
    • Key in ON position.
    • Measure the voltage between vacuum pump C1119-4, circuit 295 (LB/PK) and ground.
      Fig 26: Checking Vacuum Pump Voltage To Ground
      G03910088Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
    • Yes  : GO to G28.
    • No  : VERIFY the central junction box (CJB) fuse 27 (15A) is OK. If OK, REPAIR circuit 295 (LB/PK). TEST the system for normal operation.
  28. G28 CHECK THE VACUUM PUMP GROUND 
    • Key in OFF position.
    • Measure the resistance between vacuum pump C1119-2, circuit 57 (BK) and ground.
      Fig 27: Measuring Resistance Between Vacuum Pump C1119-2, Circuit 57 (BK) And Ground
      G03910089Courtesy of FORD MOTOR CO.
    • Is the resistance less than 5 ohms? 
    • Yes  : GO to G29.
    • No  : REPAIR circuit 57 (BK). TEST the system for normal operation.
  29. G29 CHECK THE VACUUM RESERVOIR INLET HOSE FOR BLOCKAGE 
    • Disconnect: Vacuum Reservoir Inlet Hose.
    • Connect a vacuum pump to the vacuum reservoir inlet hose and try to pull a vacuum. If the vacuum pump pulls and holds a vacuum, the hose is plugged. If the vacuum pump pulls a vacuum that slowly decays, the hose is restricted.
      Fig 28: Checking Vacuum Reservoir Hose
      G03910090Courtesy of FORD MOTOR CO.
    • Is the vacuum reservoir inlet hose plugged or restricted? 
    • Yes  : INSTALL a new vacuum reservoir inlet hose. TEST the system for normal operation.
    • No  : GO to G30.
  30. G30 CHECK THE VACUUM RESERVOIR INLET HOSE FOR A LEAK 
    • Plug the vacuum reservoir inlet hose.
      Fig 29: Identifying Vacuum Reservoir Inlet Hose
      G03924292Courtesy of FORD MOTOR CO.
    • Leak test the vacuum reservoir inlet hose using the vacuum pump.
      Fig 30: Checking Vacuum Reservoir Hose
      G03910090Courtesy of FORD MOTOR CO.
    • Does the vacuum reservoir inlet hose leak? 
    • Yes  : INSTALL a new vacuum reservoir inlet hose. TEST the system for normal operation.
    • No  : INSTALL a new vacuum pump. TEST the system for normal operation.
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