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 (WOT) in any gear range for more than 5 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 specification.

Connect pressure gauge to the line pressure tap.

Start engine and check line pressures. Refer to the following LINE PRESSURE CHART - 4.0L AND 4.6L ENGINES to determine if line pressure is within specifications.

Fig 1: Identifying Line Pressure Tap

Courtesy of FORD MOTOR CO.

LINE PRESSURE CHART - 4.0L AND 4.6L ENGINES

Range	Idle Pressure		WOT StallPressure
Range	PC C	Line	PC C	Line
N	0--103 kPa (0--15 psi)	758--1,034 kPa (110--150 psi)
R	758--862 kPa (110--125 psi)	965--1,551 kPa (140--225 psi)	758--862 kPa (110--125 psi)	2,000--2,482 kPa (290--360 psi)
(D), 2, 1	0--103 kPa (0--15 psi)	758--1,034 kPa (110--150 psi)	0--103 kPa (0--15 psi)	1,448--1,793 kPa (210--260 psi)

If line pressure is not within specification, check PC C pressure.
Connect pressure gauge to PC C pressure tap.

Fig 2: Identifying Pressure Gauge To PC 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 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 PC C boost valve PC C 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 D Only	Forward clutch Overdrive servo Intermediate servo Valve body
Low in D 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
Low in 3rd Position	Intermediate servo Overdrive servo Forward clutch