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 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 EPC, FMEM (Failure Mode Effect Management) actions. Be sure that self test and electrical repairs have been carried out, or test results may be incorrect.

This test verifies that the line pressure is within specifications.

Fig 1: Locating Line Pressure Tap

Courtesy of FORD MOTOR CO.

Connect pressure gauge to the line pressure tap on the transmission and a tachometer to the engine.

Start the engine, increase and maintain 1,000 engine RPM and check line pressures. Refer to the LINE PRESSURE CHART for specification to determine if line pressure is within specifications.

NOTE: Prior to using this chart, you should check the transmission identification tag. Some early built units will use a different specification.

LINE PRESSURE CHART

Trans.	Model Application	Range	Idle (1,000 RPM)		WOT Stall
Trans.	Model Application	Range	EPC	Line	EPC	Line
5R55E	4.0LSOHC	R	448-517 kPa (65-75 psi)	1482-1620 kPa (215-235 psi)	772-924 kPa (112-134 psi)	1944-2413 kPa (282-350 psi)
		N	138-276 kPa (20-40 psi)	517-827 kPa (75-120 psi)	-	-
		(D) 2,1	241-345 kPa (35-50 psi)	758-1000 kPa (110-145 psi)	772-924 kPa (112-134 psi)	1572-1813 kPa (228-263 psi)

If line pressure is not within specifications, check EPC pressure.

Fig 2: Identifying Electronic Pressure Control Unit

Courtesy of FORD MOTOR CO.

Connect Pressure Gauge to EPC pressure tap.
Start the engine, increase and maintain 1,000 engine RPM and check EPC pressure. See the LINE PRESSURE REFERENCE for specification.
If EPC pressure is not within specification, Go To PINPOINT TEST E: TURBINE SHAFT SPEED (TSS), INTERMEDIATE SHAFT SPEED (ISS) AND OUTPUT SHAFT SPEED (OSS) SENSORS to diagnose EPC operation. If EPC operation is OK, see the line pressure diagnosis chart for line pressure concern causes.

LINE PRESSURE DIAGNOSIS CHART

Test Results	Possible Source
High at Idle - All Ranges	Wiring Harnesses EPC Boost Valve EPC 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 Front Servo
Low in Park Only	Valve Body
Low in Reverse Only	Separator Plate Rear Servo Piston, Cover Seal Reverse Clutch Front Servo Valve Body Forward Clutch
Low in Neutral Only	Valve Body Front Servo
Low in Overdrive Only	Forward Clutch Front Servo Valve Body
Low in Drive Only (O/D Cancelled)	Forward Clutch Front Servo Valve Body
Low in 1st Position	Forward Clutch Valve Body
Low in 2nd Position	Intermediate Servo Front Servo Forward Clutch