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Line Pressure Test

CAUTION: Carry out Line Pressure Test prior to carrying out Stall Speed Test. If line pressure is low at stall, do not carry out the Stall Speed Test or further transmission damage will occur. Do not maintain wide open throttle in any gear range for more than five seconds.
NOTE: Certain sensor failures may cause high PC, FMEM (Failure Mode Effect Management) actions. Be sure that self test and electrical repairs have been carried out, or test results may be incorrect.
NOTE: The line pressure tap is used to verify output pressure from PC A or PC B by turning either one off while verifying the output from the other solenoid. The second pressure tap is used to verify the output from the PC C solenoid.

This test verifies that the line pressure is within specifications.

  1. Connect pressure gauge to the line pressure tap.
    Fig 1: Locating Line Pressure Tap
    G03281402Courtesy of FORD MOTOR CO.
  2. Start engine and check line pressures. Refer to the LINE PRESSURE CHART to determine if line pressure is within specifications.
    LINE PRESSURE CHART

    Range Idle Pressure WOT Stall Pressure
    PC C Line PC C Line
    P/N 0-69 kPa (0-10 psi) 483-620 kPa (70-90 psi) 0-69 kPa (0-10 psi) 483-620 kPa (70-90 psi)
    R 345-414 kPa (50-60 psi) 689-827 kPa (100-120 psi) 2,151-2,289 kPa (312-332 psi) 2,151-2,289 kPa (312-332 psi)
    D5 0-69 kPa (0-10 psi) 689-827 kPa (100-120 psi) 0-69 kPa (0-10 psi) 1,482-1,620 kPa (215-235 psi)
    D4 0-69 kPa (0-10 psi) 689-827 kPa (100-120 psi) 0-69 kPa (0-10 psi) 1,482-1,620 kPa (215-235 psi)
    M5/M4 0-69 kPa (0-10 psi) 689-827 kPa (100-120 psi) 0-69 kPa (0-10 psi) 1,482-1,620 kPa (215-235 psi)
    M3 0-69 kPa (0-10 psi) 689-827 kPa (100-120 psi) 0-69 kPa (0-10 psi) 1,482-1,620 kPa (215-235 psi)
    M2/M1 0-69 kPa (0-10 psi) 689-827 kPa (100-120 psi) 0-69 kPa (0-10 psi) 1,482-1,620 kPa (215-235 psi)
  3. If line pressure is not within specifications, check PC C pressure.
  4. Connect Pressure Gauge to PC C pressure tap.
    Fig 2: Locating PC C Pressure Tap
    G03281403Courtesy of FORD MOTOR CO.
  5. Start engine and check PC C pressure. Refer to LINE PRESSURE DIAGNOSIS CHART  for specification.
  6. If PC C pressure is not within specification, Go to PINPOINT TEST D: PRESSURE CONTROL (PC) SOLENOIDS (PCA, PCB, PCC)  to diagnose PC C operation. If PC C operation is OK, refer to LINE PRESSURE DIAGNOSIS CHART  for line pressure concern causes.
    LINE PRESSURE DIAGNOSIS CHART

    Test Results Possible Source
    High at Idle - All Ranges
    • Wiring Harnesses
    • EPC Boost Valve
    • EPC Solenoid
    • Main Regulator Valve
    Low at Idle - All Ranges
    • Low Fluid Level
    • Fluid Inlet Filter/Seal
    • Main Control Body
    • Cross Leaks
    • Gaskets
    • Pump
    • Separator Plate
    Low - All Forward Ranges
    • Forward Clutch
    • Main Control
    • Overdrive Servo
    • Intermediate Servo
    Low in Park Only
    • Valve Body
    Low in Reverse Only
    • Separator Plate
    • Rear Servo Piston, Cover Seal
    • Reverse Clutch
    • Overdrive Servo
    • Intermediate Servo
    • Valve Body
    • Forward Clutch
    Low in Neutral Only
    • Valve Body
    • Overdrive Servo
    • Intermediate Servo
    Low in Overdrive Only
    • Forward Clutch
    • Overdrive Servo
    • Intermediate Servo
    • Valve Body
    Low in Drive Only (O/D Cancelled)
    • Forward Clutch
    • Overdrive Servo
    • Intermediate Servo
    • Valve Body
    Low in 1st Position
    • Forward Clutch
    • Valve Body
    Low in 2nd Position
    • Intermediate Servo
    • Overdrive Servo
    • Intermediate Servo
    • Forward Clutch
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