Stall Speed Test

4R70E/4R75E

Stall Speed Test

WARNING: Block all wheels, set the parking brake and firmly apply the service brake to reduce the risk of vehicle movement during this procedure. Failure to follow these instructions may result in serious personal injury.

NOTICE: Carry out Line Pressure Test prior to carrying out Stall Speed Test. If the line pressure is low at stall, do not carry out Stall Speed Test or further transmission damage will occur. Line Pressure Test

The Stall Speed Test checks the following:

- Torque Converter Clutch (TCC) operation and installation
- Holding ability of the forward clutch
- Reverse clutch (the low-reverse bands)
- Planetary One-Way Clutch (OWC)
- Engine driveability

Conduct this test with the engine coolant and transmission fluid at correct levels and at normal operating temperature.

Apply the park brake firmly for each Stall Speed Test.

1. Find the specified stall rpm for the vehicle; refer to the Stall Speed chart.

Stall Speed:

2. Connect a scan tool.

3. NOTE: If the engine rpm recorded by the scan tool exceeds the maximum limits, release the accelerator pedal immediately because clutch or band slippage is indicated.

In each of the following selector lever positions, R, (D), 2, 1 press the accelerator pedal to the floor and hold it just long enough to let the engine get to Wide Open Throttle (WOT). While conducting this test, do not hold the throttle plate open for more than 5 seconds at a time.

4. Note the results in each position.

5. After each position, move the selector lever to NEUTRAL and run the engine at 1,000 rpm for about 15 seconds to cool the torque converter before making the next test.

6. Refer to the Stall Speed Diagnosis Chart for corrective actions.

Stall Speed Diagnosis Chart: