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 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: Connecting Pressure Gauge To 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.

LINE PRESSURE CHART - 3.0L AND 3.9L ENGINES

Range	Idle Pressure		WOT Stall Pressure
Range	PC C	Line	PC C	Line
P/N	1-103 kPa (0-15 psi)	862-1,137 kPa (125-165 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)
D5	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)
D4	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)
M5/M4	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)
M3	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)
M2/M1	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 specifications, check PC C pressure.
Connect Pressure Gauge to PC C pressure tap.

Fig 2: Connecting Pressure Gauge To PC C Pressure Tap
Courtesy of FORD MOTOR CO.
Start engine and check PC C pressure. Refer to LINE PRESSURE DIAGNOSIS CHART in this article 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 in this article 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 D5 Only	Forward Clutch
	Overdrive Servo
	Intermediate Servo
	Valve Body
Low in D4 Only (O/D Cancelled)	Forward Clutch
	Overdrive Servo
	Intermediate Servo
	Valve Body
Low in First Position	Forward Clutch
Low in First Position	Valve Body
Low in Second Position	Intermediate Servo
	Overdrive Servo
	Intermediate Servo
	Forward Clutch
Low in Third Position	Intermediate servo
	Overdrive servo
	Forward clutch