Line Pressure Test

WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Locating Line Pressure Tap Plug

Courtesy of FORD MOTOR CO.

NOTE: Carry out the Line Pressure Test prior to carrying out the Stall Speed Test. If the line pressure is low at stall, do not carry out the Stall Speed Test or further transaxle damage will occur. Do not maintain Wide Open Throttle (WOT) in any transaxle range for more than 5 seconds.

This test verifies that the line pressure is within specification.

Connect the Transmission Fluid Pressure Gauge to the line pressure tap.

Start the engine and check the line pressures see the LINE PRESSURE CHART to determine if the line pressure is within specification.

LINE PRESSURE CHART

Gear

Line

Pressures at Idle ⁽¹⁾

338-379 kPa (49-55 psi)

621-689 kPa (90-100 psi)

338-379 kPa (49-55 psi)

Pressure at Wide Open Throttle (WOT) Stall ^a

N/A

1, 868-2, 068 kPa (271-300 psi)

N/A

1, 868-2, 068 kPa (271-300 psi)

⁽¹⁾	All pressures are approximate.

If the line pressure is not within specification, GO to PINPOINT TEST A to diagnose the Line Pressure Control (LPC) operation. If LPC operation is OK, see the Line Pressure Diagnosis Chart for line pressure concern causes.

Once Line Pressure Test is complete, install the line pressure tap plug.

Tighten to 12 Nm (106 lb-in).

LINE PRESSURE DIAGNOSIS CHART

Test Results	Possible Source
HIGH at IDLE - ALL RANGES	Wiring Harnesses Line Pressure Control (LPC) Solenoid Main Regulator Valve
LOW at IDLE - ALL RANGES	Low Transmission Fluid Fluid Inlet Filter/Seal Main Control Body Cross Leaks Gaskets Pump Separator Plate
LOW in Park ONLY	Valve Body
LOW in Reverse ONLY	Separator Plate Reverse Clutch Valve Body Forward Clutch
LOW in Neutral ONLY	Valve Body
LOW in Overdrive ONLY	Forward Clutch Valve Body
LOW in Drive ONLY	Forward Clutch
LOW in Manual 1st ONLY	Forward Clutch Valve Body