Line Pressure Test
WARNING: This page is about a different car, the 2024 Ford Transit-350 HD, 2024 Ford Transit-350, 2024 Ford Transit-250, and 2024 Ford Transit-150. However, it is still accessible from the selected car via links, so may be relevant.
NOTE:
Carry out the Line Pressure Test prior to the Stall Speed Test. If line pressure is low, do not carry out the stall test or additional transmission damage will occur. Do not maintain Wide Open Throttle (WOT) in any gear range for more than 5 seconds.
This test verifies the line pressure is within specification.
- Remove the front subframe. REFER to: FRONT SUBFRAME .
- 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 an 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, use the scan tool to carry out the LPC Line Pressure Cycling located in the Transmission Accelerated Main Control Break In Routine application. After completing the LPC Line Pressure Cycling Routine, recheck the line pressure. If the line pressure is still 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 13.5 Nm (120 lb-in).
| Test Results | Possible Source |
|---|---|
| HIGH at IDLE | Wiring harnesses LPC solenoid LPC valve |
| LOW at IDLE OR Does not change when commanding LINESD# up and down |
LPC solenoid mechanically stuck OFF Fluid inlet filter/seal Transmission fluid pump gasket or seal Transmission fluid pump gear teeth damaged Main control valve body Main pressure regulator valve stuck in spring compressed position Broken or missing main pressure regulator valve spring Transmission fluid 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.