Line Pressure Test
WARNING: This page is about a different car, the 2008 Ford RV Cutaway, 2008 Ford Econoline, and 2008 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
CAUTION:
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 Stall Speed Test or further transmission damage will occur. Do not maintain wide open throttle (WOT) in any transmission range for more than 5 seconds.
| Item | Part Number | Description |
|---|---|---|
| 1 | - | Direct clutch pressure tap |
| 2 | - | Forward clutch pressure tap |
| 3 | - | Electronic pressure control (EPC) pressure tap |
| 4 | - | Intermediate clutch pressure tap |
| 5 | - | Line pressure tap |
This test verifies that the line pressure is within specification.
- Connect pressure gauge to line pressure tap.
- Start engine and check line pressures. Refer to the Line Pressure Chart to determine if line pressure is within specification.LINE PRESSURE CHART
Applications Range Idle WOT EPC Line Pressure EPC Line Pressure All applications P, N 0-138 kPa
(0-20 psi)207-448 kPa (30-65 psi) N/A N/A All applications OD, 2, 1 138-345 kPa (20-50 psi) 345-758 kPa (50-110 psi) 655-793 kPa (95-115 psi) 1,310-1,586 kPa (190-230 psi) All applications R 138-345 kPa (20-50 psi) 552-1034 kPa (80-150 psi) 552-655 kPa (80-95 psi) 1,379-1,931 kPa (200-280 psi) - Place the ignition switch in the OFF position. If line pressure is not within specification, check electronic pressure control (EPC) pressure.
- Connect pressure gauge to EPC pressure tap.
- Start engine and check EPC pressure. Use the Line Pressure Chart for specifications.
- If EPC pressure is not within specification, go to Pinpoint Test E 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 - In All Positions | Wiring Harnesses |
| Run Quick Test. Refer to the appropriate Engine Performance article. | |
| EPC Solenoid | |
| Main Regulator Valve | |
| Low At Idle - In All Positions | Low Transmission Fluid Level |
| Control Body | |
| Leakage in Pump | |
| Damaged Gaskets on Separator Valve | |
| Damaged Separator Plate | |
| Restricted Inlet Filter | |
| Case Bolts | |
| Loose Main Control Valve Body | |
| EPC Solenoid O-Ring | |
| EPC Solenoid Bracket | |
| Case | |
| Sticking Main Regulator Valve | |
| Damaged Inlet Tube Seal on Inlet Filter | |
| Low In PARK Only | Valve Body |
| Low/Reverse Servo | |
| Low In REVERSE Only | Separator Plate |
| Low/Reverse Servo or Valve Body | |
| Reverse Clutch | |
| Low In NEUTRAL Only | Valve Body |
| Low In OVERDRIVE Only | Forward Clutch |
| Valve Body | |
| Low In 1st Position Only | Forward Clutch |
| Valve Body | |
| Low/Reverse Servo | |
| Low In 2nd Position Only | Intermediate Clutch |
| Valve Body | |
| Forward Clutch |