Line Pressure Test

WARNING: This page is about a different car, the 2002 Infiniti QX4, 2001 Nissan Pathfinder, and 2001 Infiniti QX4. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Always replace line pressure plugs, as they are self-sealing bolts.

Check transmission fluid and engine oil levels. If necessary, add fluid or oil.
Drive vehicle for about 10 minutes or until engine oil and transmission fluid reach operating temperature. Transmission fluid operating temperature should be 122-176°F (50-80°C).
Install pressure gauge to corresponding line pressure port. See Fig 1.
Set parking brake and block wheels. Continue to depress brake pedal fully while line pressure test is being performed at stall speed.
Start engine and measure line pressure at idle and stall speed. When measuring line pressure at stall speed, follow the stall test procedure. See STALL SPEED TEST . Note pressure readings and see LINE PRESSURE SPECIFICATIONS table. Compare hydraulic pressure test results with the following symptoms:
- Line Pressure Low At Idle In All Positions
  
  Oil pump wear, control piston damage, pressure regulator valve or plug sticking, or fluid pressure leakage between oil strainer and pressure regulator.
- Line Pressure Low At Idle In A Particular Position
  
  Check for fluid pressure leakage between manual valve and the particular clutch.
- Line Pressure High At Idle
  
  Misadjusted TP sensor, fluid temperature sensor or line pressure solenoid damaged, pressure modifier valve sticking or pressure regulator valve sticking. Open in dropping resistor circuit.
- Line Pressure Low At Stall Speed
  
  Misadjusted TP sensor, control piston damaged, short in line pressure solenoid circuit, line pressure solenoid sticking, pressure regulator valve or plug sticking, or pressure modifier valve or pilot valve sticking.

LINE PRESSURE SPECIFICATIONS

Application		Pressure - psi (kPa)
At Idle
"D", "2" & "1" Positions		61-67 (422-461)
"R" Position		97-102 (667-706)
At Stall Speed
"D", "2" & "1" Positions		148-159 (1020-1098)
"R" Position		206-218 (1422-1500)

Fig 1: Locating Line Pressure Test Ports

Courtesy of NISSAN MOTOR CO., U.S.A.