Transmission Line Pressure Test
WARNING: This page is about a different car, the 2018 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.
Line Pressure Test
NOTE:
Perform the line pressure test prior to performing the stall speed test. If the line pressure is low at stall, do not perform the stall speed test or transmission damage will occur. Do not maintain WOT in any transmission range for more than 5 seconds.
This test verifies the line pressure is within specification.
- Remove the air cleaner. REFER to: Air Cleaner .
- Loosen the transmission fluid cooler line fittings from the bypass valve.
- Remove the nuts and position aside the transmission fluid bypass valve.
- Remove the line pressure tap plug.
- Connect the transmission fluid pressure gauge (307-004) to the line pressure tap.
- Position back the transmission bypass valve and tighten the fluid cooler line fittings.
- Torque: 30 Nm (22 lb-in).
- Install the air cleaner. REFER to: Air Cleaner .
- Start the engine and check the line pressure.
- Compare the PID LINEDSD# to actual measured pressure. Actual measured pressure should be within 10 PSI (69 kPa). Raise engine RPM to 2000 RPM, Verify LPC operation by monitoring LINE pressure while commanding the PID LINEDSD# up and down.
- If the measured line pressure is not within 10 PSI (69 kPa) of the PID LINEDSD#, see the Line Pressure Diagnosis Chart below for possible source.
- When the pressure tests are complete, stop the engine.
- Remove the air cleaner. REFER to: Air Cleaner .
- Loosen the transmission fluid cooler line fittings and position aside the bypass valve.
- Remove the transmission fluid pressure gauge and install the line pressure tap plug.
- Torque: 12 Nm (106 lb-in).
- Position back the transmission fluid bypass valve and install the nuts.
- Torque: 11 Nm (97 lb-in).
- Tighten the transmission fluid cooler line fittings.
- Torque: 30 Nm (22 lb-in).
- Install the air cleaner. REFER to: Air Cleaner .
Line Pressure Diagnosis Chart
| Test Results | Possible Source |
|---|---|
| HIGH at IDLE | Wiring Harnesses (open circuit/high resistance to LPC) LPC solenoid mechanically stuck ON Verify LPC operation by monitoring LINE pressure while commanding LINEDSD# up and down |
| Main pressure regulator valve stuck in default position | |
| LOW at IDLE | Low Transmission Fluid level |
| LPC solenoid mechanically stuck OFF Verify LPC operation by monitoring LINE pressure while commanding LINEDSD# up and down Fluid Inlet Filter/Seal Main pressure regulator valve stuck in spring compressed position Broken or missing main pressure regulator valve spring Pump |