Line Pressure Test

4R70E/4R75E

Special Testing Procedures





The special tests are designed to aid the technician in diagnosing the hydraulic and mechanical portion of the transmission.

Line Pressure Test

NOTICE: 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 (TR) for more than 5 seconds.

This test verifies that the line pressure is within specification.

1. Connect the Transmission Fluid Pressure Gauge to the line pressure tap.

2. Start engine and check line pressures. Refer to the Line Pressure Chart to determine if line pressure is within specification.

Line Pressure Chart:

3. Place the ignition switch in the OFF position. If line pressure is not within specification, check Electronic Pressure Control (EPC) pressure.

4. Connect the Transmission Fluid Pressure Gauge to the EPC pressure tap.

5. Start the engine and check EPC pressure. Refer to the Line Pressure Chart for specifications.

6. If the EPC pressure is not within specification, Go To Pinpoint Test D Pinpoint Test D: EPC Solenoid to diagnose EPC operation. If EPC operation is OK, refer to the Line Pressure Diagnosis Chart for line pressure concern causes.

7. When the pressure tests are completed, install the pressure tap plugs.
- Tighten to 12 Nm (106 lb-in).

Line Pressure Diagnosis Chart: