Line Pressure Test
WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
This test verifies the line pressure is within specification.
- If equipped, remove the heat shield.
- Remove the 2 bolts. Torque: 10Nm (88 lb-in)
- Remove the push pin and the heat shield.
- Connect the transmission fluid pressure gauge (307-004) to the line pressure tap using an M10 X 1.00 fitting.NOTE: The line pressure tap is an M10 X 1.00 thread. Do not us a National Pipe Thread (NPT) fitting when installing a pressure gauge. If a NPT fitting is used, damage to the transmission case will occur.
- Start the engine and check the line pressure.
- Using a diagnostic scan tool, monitor and compare the PID LINEDSD# to actual measured pressure. Actual measured pressure should be within 10 PSI (69 kPa). Raise engine RPM to 2000 RPM and verify LPC operation by monitoring LINE pressure while commanding LINEDSD# up and down.
- If the line pressure is not within specification, see the Line Pressure Diagnosis Chart for possible sources.
- When the pressure tests are complete, install the line pressure tap plug.
- Tighten to 11 Nm (97 lb-in).
Line Pressure Diagnosis Chart
| Test Results | Possible Source |
|---|---|
| HIGH at IDLE | Wiring harnesses LPC solenoid LPC valve |
| LOW at IDLE OR Does not change when commanding LINEDSD# up and down |
LPC solenoid mechanically stuck OFF Fluid inlet filter/seal Main control valve body Main pressure regulator valve stuck in spring compressed position Broken or missing main pressure regulator valve spring Pump Separator plate |
A no-drive condition can exist even with correct transmission fluid pressure because of inoperative clutches. Refer to the Clutch Application Chart to determine which clutch is applied in each gear range. A clutch concern can be further diagnosed by performing the air pressure test.