TCC Surge/Chuggle/Slip at 72-96 km/h (45-60 mph) with Automatic Transmission 4T40E (Reprogram PCM)

Some owners may comment on a TCC surge/chuggle between 72-96 km/h (45-60 mph) under a light load with the engine at operating temperature and TCC applied. There will be no stored DTCs. When in the condition, a Tech 2 will reveal that TCC slip will oscillate for multiple consecutive cycles (3 or more) between 20-300 RPM slip. The driver may notice a fluctuation in the tachometer at steady highway speeds and may also notice a vehicle surging sensation.

Condition may be caused by a variation in the torque converter clutch slip speed.

Test drive the vehicle. Look for a fluctuation of 20-300 RPM in the torque converter slip speed with a steady TCC duty cycle of 25-50%. Commanding the TCC fully on (99% PWM) will eliminate the concern. If the vehicle exactly duplicates the above conditions, recalibrate the PCM with the appropriate calibration.

Remember that the calibration is VIN specific. When you enter the VIN, the correct calibration will appear. The calibrations listed are electronic calibrations and are NOT available from GMSPO. Calibrations will be available from Techline starting June 2001, on the TIS 2000 version 7.0.

For vehicles repaired under warranty, use: