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Home >> Ford >> 2012 >> Mustang Base, 2D Coupe, Automatic Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 144 (Four Wheel Drive (4WD) Systems -- F150) >> 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 2012 Ford Pickup. 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 
  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? 
  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? 
  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? 
  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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