Line Pressure Test

Special Testing Procedures





Special Tool(s)

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

Line Pressure Test





CAUTION: Carry out the Line Pressure Test prior to carrying out the Stall Speed Test. If line pressure is low at stall, do not carry out the Stall Speed Test or additional transmission damage will occur. Do not maintain wide-open throttle (WOT) in any transmission range for more than 5 seconds or transmission damage may occur.

CAUTION: Apply the parking brake and block drive wheels during the line pressure test. Vehicle movement during the test may cause personal injury or damage to the vehicle and equipment.

NOTE: Certain sensor failures may cause high control pressure and Failure Mode Effect Management (FMEM) actions. Make sure that on-board diagnostic and electrical repairs have been carried out, or test results may be incorrect.

This test verifies the line pressure is within specifications.
1. Connect the Pressure Gauge to the line pressure tap.
2. Start the engine and check the line pressures at idle speeds with the transmission in each gear range. Refer to the Line Pressure Chart to determine if the line pressure is within specification.

3. CAUTION: Do not immediately press the throttle to the floor or allow the throttle to immediately close, or internal damage to the engine or transmission will occur.

Check line pressure at Wide Open Throttle (WOT) stall speed with the range selector lever in all gear ranges. Slowly press the throttle to WOT record the pressure reading. After recording the pressure reading slowly release the throttle until closed throttle is obtained (idle). Refer to the Line Pressure Chart to determine if the line pressure is within specification.

4. If pressure is not within specification, refer to the Line Pressure Chart for further diagnosis.





Pressure Chart A

NOTE: Actual and Commanded pressures will vary based on calibration and transmission adaptive Strategies. All pressures listed are approximate.

Part 1 Of 2:

Part 2 Of 2:

Pressure Chart B

NOTE: Actual and Commanded pressures will vary based on calibration and transmission adaptive strategies. All pressures listed are approximate.





Pressure Chart C

NOTE: Actual and Commanded pressures will vary based on calibration and transmission adaptive strategies. All pressures listed are approximate.





Pressure Chart D

NOTE: Actual and Commanded pressures will vary based on calibration and transmission adaptive strategies. All pressures listed are approximate.





Line Pressure Diagnostic Chart