Line Pressure Test

WARNING: This page is about a different car, the 2002 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: Carry out Line Pressure Test prior to carrying out Stall Speed Test. If 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 in any gear range for more than five seconds.

NOTE: Certain sensor failures may cause high EPC, FMEM (Failure Mode Effect Management) actions. Be sure that self test and electrical repairs have been carried out, or test results may be incorrect.

This test verifies that the line pressure is within specifications.

Fig 1: Identifying Line Pressure Tap

Courtesy of FORD MOTOR CO.

Connect pressure gauge to the line pressure tap on the transmission and a tachometer to the engine.
Start the engine, increase and maintain 1,000 engine RPM and check line pressures. Refer to the line pressure chart in Diagnostics for specification to determine if line pressure is within specifications. See Fig 2.

Fig 2: Line Pressure Chart
Courtesy of FORD MOTOR CO.
If line pressure is not within specifications, check EPC pressure.

Fig 3: Locating Electronic Pressure Control (EPC) Pressure Tap
Courtesy of FORD MOTOR CO.
Connect Pressure Gauge to EPC pressure tap.
Start the engine, increase and maintain 1,000 engine RPM and check EPC pressure. See the line pressure chart for specification.
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.

Fig 4: Line Pressure Diagnosis Chart
Courtesy of FORD MOTOR CO.