GM Service Manual Online
For 1990-2009 cars only

The stall speed test validates the overall performance of the transaxle and the engine by measuring the maximum engine speeds in the forward and reverse ranges.

    Notice: This test should always be performed at a normal operating fluid temperature of 70 to 80°C (158 to 176°F). DO NOT run engine at stall speed for more than five seconds continuously. If this precaution is not observed, engine oil and transaxle fluid temperatures may rise excessively high.

  1. Connect the scan tool to the Data Link Connector (DLC) and display the engine rpm.
  2. Apply the parking brake and block the vehicle wheels.
  3. Turn the ignition switch to the ON position.
  4. Press the brake pedal fully.
  5. Ensure that the manual selector lever is in the park (P) range.
  6. Start the engine.
  7. Move the manual selector lever to the drive (D) range.
  8. Press the accelerator pedal fully at Wide Open Throttle (WOT). While watching the scan tool, quickly read and record the engine speed (RPM) once it becomes constant (stall speed).
  9. Release the accelerator pedal immediately after the stall speed is recorded.
  10. Using the same method, record the stall speed in Second 2, Low L, and Reverse (R) ranges.
  11. Return the selector lever to park (P) range and turn the ignition switch to LOCK.

Evaluation

The stall speed should fall within 2000 to 2500 RPM in all tested gear ranges. Refer to the Stall Speed Test Diagnosis for causes of higher or lower stall speed.

Stall Speed Test Diagnosis

Stall Speed Test Results

Road Test Results

Probable Cause

Stall Speed in All Gear Ranges Exceed Specified Limit

No 1st gear or slippage in 1st gear.

Line pressure too low.

Stall Speed in Drive (D) and Second (2) Ranges Exceed Specified Limit

    • Slippage in 1st gear.
    • 2nd and 3rd gear are normal.
    • Slippage in drive (D) range 1st, 2nd and 3rd gears. Engine braking occurs with throttle valve fully closed.
    • Slippage in Second (2) range 1st and 2nd gears. Engine braking occurs with throttle valve fully closed.
    • One-way clutch slippage.
    • One-way clutch slippage.
    • Forward clutch.
    • Forward clutch.

Stall speed in Reverse (R) Range Exceeds the Specified Limit

    • Engine braking does not function in the Low (L) range.
    • Engine braking works in the L range
    • 1st-reverse brake slippage.
    • Direct clutch slippage.

Stall Speed Within Specifications

    • Vehicle speed will not exceed 50 km/h (50 mph). This condition causes very high fluid temperatures.
    • Slippage in drive (D) range 3rd gear.
    • Slippage in drive (D) range 1-2 gear upshift.
    • Torque converter one-way clutch seizure.
    • Direct clutch slippage.
    • 2nd brake band slippage.