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Line Pressure Test

CAUTION: Carry out the Line Pressure Test prior to carrying out the Stall Speed Test . If the line pressure is low at stall, do not carry out Stall Speed Test  or further transmission damage will occur. Do not maintain wide open throttle (WOT) in any transmission range for more than 5 seconds.

This test verifies that the line pressure is within specification.

  1. Connect a pressure gauge to the line pressure tap.
  2. Start the engine and check line pressures. Refer to the LINE PRESSURE TABLE  to determine if line pressure is within specification.
    LINE PRESSURE TABLE

    Applications Range Idle WOT
    EPC Line Pressure EPC Line Pressure
    All P, N 34-276 kPa (5-40 psi) 276-689 kPa (40-100 psi) N/A N/A
      OD, 2, 1 34-276 kPa (5-40 psi) 276-689 kPa (40-100 psi) 689-793 kPa (100-115 psi) 1,172-1,586 kPa (170-230 psi)
      R 172-207 kPa (25-30 psi) 689-862 kPa (100-125 psi) 586-655 kPa (85-95 psi) 1,124-2,068 kPa (250-300 psi)
  3. Place the ignition switch in the OFF position. If line pressure is not within specification, check EPC pressure.
  4. Connect a pressure gauge to the EPC pressure tap.
  5. Start the engine and check EPC pressure. Use LINE PRESSURE DIAGNOSIS TABLE  for specifications.
  6. If the EPC pressure is not within specification, GO to PINPOINT TEST D  to diagnose the EPC operation. If the EPC operation is OK, refer to the LINE PRESSURE DIAGNOSIS TABLE  for line pressure concern causes.
LINE PRESSURE DIAGNOSIS TABLE

Test Results Possible Source
High at Idle in All Positions
Low at Idle in All Positions
  • Low fluid level
  • Restricted inlet filter
  • Damaged inlet tube seal on inlet filter
  • Loose main control valve bodies
  • Sticking main regulator valve
  • Excessive leakage in pump
  • Damaged gaskets on separator valve
  • Case bolts
  • Case
  • Separator plate
  • EPC solenoid
Low in Park Only
  • Valve body
  • Low/reverse servo
Low in Reverse Only
  • Separator plate
  • Low/rear servo or valve body
  • Reverse clutch
Low in Neutral Only
  • Valve body
Low in Overdrive Only
  • Forward clutch
  • Valve body
Low in 1st Position
  • Forward clutch
  • Valve body
  • Low/reverse servo
Low in 2nd Position
  • Intermediate clutch
  • Valve body
  • Forward clutch