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.

Connect pressure gauge to the line pressure tap.

Fig 1: Identifying Line Pressure Tap
Courtesy of FORD MOTOR CO.
Start engine and check line pressures. Refer to the following Line Pressure Chart to determine if line pressure is within specifications.

Fig 2: Line Pressure Chart - 3.9L Engine
Courtesy of FORD MOTOR CO.
If line pressure is not within specifications, check PC C pressure.
Connect Pressure Gauge to PC C pressure tap.

Fig 3: Identifying PC C Pressure Tap
Courtesy of FORD MOTOR CO.
Start engine and check PC C pressure. Refer to LINE PRESSURE DIAGNOSIS CHART for specification.
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.