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Home >> Ford >> 2012 >> Mustang Base, 2D Coupe, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 557 (Four Wheel Drive (4WD) Systems) >> Diagnosis And Testing >> Four Wheel Drive (4WD) Systems - Electronic Shift >> Pinpoint Tests >> Pinpoint Test F: The Front Axle Makes Noise in 2H Mode Only and Generally Under Heavy Throttle >> Pinpoint Test F: The Front Axle Makes Noise In 2H Mode Only And Generally Under Heavy Throttle

Pinpoint Test F: The Front Axle Makes Noise In 2H Mode Only And Generally Under Heavy Throttle

WARNING: This page is about a different car, the 2014 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
WARNING: When directed to drive the vehicle as part of this test, drive the vehicle on a hard surface in an area without traffic to prevent a crash. Failure to follow these instructions may result in personal injury.
  1. F1 CHECK FOR GRINDING NOISES AT HIGH SPEEDS 
    • With the vehicle warm and the MSS  in 2H mode, drive the vehicle at sustained WOT  for 5 seconds.

    Is there a grinding noise from the axle system during WOT ? 

  2. F2 CHECK THE IWE SOLENOID OUTPUT VACUUM IN 2H 
    • NOTE: The engine must be idling during the following steps to supply the vacuum required for the IWEs  to engage and disengage.

      Start the engine.

    • Disconnect the output vacuum line at the IWE  solenoid while having the vacuum supply attached to the solenoid.
    • With the engine running and the transfer case in 2H mode, measure the vacuum at the output port of the IWE  solenoid.

    Is the vacuum greater than 254 mm (10 in) Hg? 

    • Yes  : GO to  F7.
    • No  : GO to F3  .
  3. F3 CHECK THE IWE SOLENOID INPUT VACUUM 
    • Disconnect the supply vacuum line at the IWE  solenoid.
    • NOTE: The engine must be idling during the following steps to supply the vacuum required for the IWEs  to engage and disengage.

      With the engine still running, measure the supply line vacuum to the IWE  solenoid.

    Is the vacuum greater than 254 mm (10 in) Hg? 

    • Yes  : INSTALL a new IWE  solenoid. TEST the system for normal operation.
    • No  : GO to F4  .
  4. F4 CHECK SOURCE VACUUM TO THE VACUUM RESERVOIR 
    • Disconnect the source vacuum line from the vacuum reservoir.
    • NOTE: The engine must be idling during the following steps to supply the vacuum required for the IWEs  to engage and disengage.

      With the engine still running, measure the source vacuum being supplied to the vacuum reservoir.

    Is the vacuum greater than 254 mm (10 in) Hg? 

    • Yes  : GO to F5  .
    • No  : REPAIR or INSTALL a new source vacuum line. TEST the system for normal operation.
  5. F5 CHECK THE VACUUM RESERVOIR 
    • Ignition OFF.
    • Disconnect the vacuum line from the vacuum reservoir.
    • Connect a vacuum pump to the source vacuum port on the vacuum reservoir and apply 508 mm (20 in) Hg of vacuum.

    Does the vacuum maintain or drop less than 25 mm (1 in) Hg per minute? 

    • Yes  : GO to F6  .
    • No  : INSTALL a new vacuum reservoir. TEST the system for normal operation.
  6. F6 CHECK THE VACUUM CHECK VALVE 
    • NOTE: The check valve is between the vacuum source and the IWE  solenoid and vacuum reservoir.

      Connect the vacuum lines to the IWE  solenoid.

    • Connect a vacuum pump to the IWE  solenoid vacuum line at the vacuum reservoir and apply 508 mm (20 in) Hg of vacuum.

    Does the vacuum maintain or drop less than 25 mm (1 in) Hg per minute? 

    • Yes  : Concern not present at this time. CARRY OUT the ESOF  Functional Test. GO to PINPOINT TEST I .
    • No  : REPAIR or INSTALL new vacuum lines or INSTALL a new check valve. TEST the system for normal operation.
  7. F7 CHECK THE IWE VACUUM SYSTEM 
    • Ignition OFF.
    • Disconnect both vacuum lines from the IWE  solenoid.
    • Using a vacuum pump, apply 508 mm (20 in) Hg of vacuum to the IWE  system through the apply vacuum circuit.
    • Observe the vacuum reading.

    Does the vacuum maintain or drop less than 25 mm (1 in) Hg per minute? 

    • Yes  : CONNECT the vacuum lines to the IWE  solenoid. GO to  F11.
    • No  : GO to F8  .
  8. F8 CHECK THE RH IWE LEAK RATE 
    • With the vehicle in NEUTRAL, position it on a hoist. Refer to JACKING & LIFTING .
    • Disconnect the vacuum line from the larger port on the RH IWE  .
    • Apply 508 mm (20 in) Hg of vacuum to the RH IWE  port and observe vacuum reading.

    Does the vacuum maintain or drop less than 25 mm (1 in) Hg per minute? 

    • Yes  : GO to F9  .
    • No  : INSTALL a new RH IWE  . REFER to INTEGRATED WHEEL END (IWE) . TEST the system for normal operation.
  9. F9 CHECK THE LH IWE LEAK RATE 
    • Disconnect the vacuum line from the larger port at the LH IWE  .
    • Apply 508 mm (20 in) Hg of vacuum to the LH IWE  port and observe vacuum reading.

    Does the vacuum maintain or drop less than 25 mm (1 in) Hg per minute? 

    • Yes  : GO to F10  .
    • No  : INSTALL a new LH IWE  . REFER to INTEGRATED WHEEL END (IWE) . TEST the system for normal operation.
  10. F10 CHECK THE IWE VACUUM SUPPLY TUBE 
    • Disconnect both vacuum lines from the IWE  solenoid.
    • Plug both LH and RH IWE  vacuum lines. Apply 508 mm (20 in) Hg of vacuum to the IWE  apply vacuum circuit and observe the vacuum reading.

    Does the vacuum maintain or drop less than 25 mm (1 in) Hg per minute? 

    • Yes  : GO to F11  .
    • No  : INSTALL new vacuum lines as necessary. TEST the system for normal operation.
  11. F11 CHECK THE IWE VACUUM SUPPLY AT EACH IWE IN 2H 
    • Connect the vacuum lines to the IWE  solenoid.
    • Connect a hand-held vacuum gauge to the LH IWE  vacuum supply tube.
    • NOTE: The engine must be idling during the following steps to supply the vacuum required for the IWEs  to engage and disengage.

      Start the engine.

    • Switch the MSS  to 2H mode while observing the vacuum gauge.
    • Repeat these steps for the RH IWE  .

    Are the vacuum readings greater than 254 mm (10 in) Hg? 

    • Yes  : GO to F12  .
    • No  : INSTALL new vacuum lines as necessary. TEST the system for normal operation.
  12. F12 CHECK THE LH IWE VACUUM LINE FOR AN OBSTRUCTION 
    • Ignition OFF.
    • Disconnect both vacuum lines from the IWE  solenoid.
    • With the vehicle in NEUTRAL, position it on a hoist. Refer to JACKING & LIFTING .
    • Disconnect the vacuum line at the LH IWE  .
    • Connect a hand vacuum pump to the LH IWE  vacuum line and attempt to draw a vacuum on the line.

    Did the vacuum pump draw a vacuum on the LH IWE vacuum line? 

    • Yes  : INSTALL a new vacuum line. TEST the system for normal operation.
    • No  : CONNECT the vacuum line to the LH IWE  . GO to F13  .
  13. F13 CHECK THE RH IWE VACUUM LINE FOR AN OBSTRUCTION 
    • Disconnect the larger vacuum line at the RH IWE  .
    • Connect a vacuum pump to the RH IWE  vacuum line and attempt to draw a vacuum on the line.

    Did the vacuum pump draw a vacuum on the RH IWE vacuum line? 

    • Yes  : INSTALL a new vacuum line. TEST the system for normal operation.
    • No  : CONNECT the vacuum line to the RH IWE  . GO to F14  .
  14. F14 CHECK THE LH IWE OPERATION 
    • Connect a vacuum pump with gauge to the larger port of the LH IWE  .
    • Observe the LH halfshaft while rotating the LH front tire. Apply between 152 and 203 mm (6 to 8 in) Hg of vacuum and release the vacuum to manually disengage and engage the LH IWE  .

    Did the LH IWE disengage between 152 and 203 mm (6 to 8 in) Hg and engage when the vacuum is released? 

    • Yes  : GO to F15  .
    • No  : INSTALL a new LH IWE  . REFER to INTEGRATED WHEEL END (IWE) . TEST the system for normal operation.
  15. F15 CHECK THE RH IWE OPERATION 
    • Connect a vacuum pump with gauge to the larger port of the RH IWE  .
    • Observe the RH halfshaft while rotating the RH front tire. Apply between 152 and 203 mm (6 to 8 in) Hg of vacuum and release the vacuum to manually disengage and engage the RH IWE  .

    Did the RH IWE disengage between 152 and 203 mm (6 to 8 in) Hg and engage when the vacuum is released? 

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