Upshift Control and Torque Converter Clutch (TCC) Apply

The PCM/TCM calculates the upshift points based primarily on two inputs: throttle angle and vehicle speed. When the PCM/TCM determines that conditions are met for a shift to occur, the PCM/TCM commands the shift by closing or opening the ground circuit for the appropriate solenoid.

Perform the following steps:

1. Refer to the Shift Speed (M30/M32/M70) or Shift Speed (M33 Only) and choose a throttle position. Table throttle angles shown should be tested to cover the normal driving range.
2. Monitor the following scan tool parameters:
   • Throttle angle
   • Vehicle speed
   • Engine speed
   • Transmission input speed sensor - some models
   • Output shaft speed
   • Commanded gear
   • Slip speed
   • Solenoid states
3. Place the gear selector in the OVERDRIVE position.
4. Accelerate the vehicle using the chosen throttle angle. Hold the throttle steady.
5. As the transmission upshifts, note the vehicle speed when the shift occurs for each gear change. There should be a noticeable shift feel or engine speed change within 1 to 2 seconds of the commanded gear change.
6. Compare the shift speeds to the Shift Speed table. Refer to Shift Speed (M30/M32/M70) or Shift Speed (M33 Only) . Shift speeds may vary slightly due to transmission fluid temperature or hydraulic delays in responding to electronic controls.
   • Note any harsh, soft or delayed shifts or slipping.
   • Note any noise or vibration.
7. Repeat steps 1 through 6 as necessary in order to evaluate the different throttle angles.
IMPORTANT: This transmission is equipped with an electronically controlled capacity clutch (ECCC). The pressure plate does not fully lock to the torque converter cover. Instead, the pressure plate maintains a small amount of slippage, about 20 RPM, in SECOND, THIRD and FOURTH gears, depending on the vehicle application. ECCC was developed to reduce the possibility of noise, vibration or chuggle caused by TCC apply. Typical apply speeds are 49-52 km/h (30-32 mph) in THIRD gear and 65-73 km/h (40-45 mph) in FOURTH gear. Full lockup is available at highway speeds on some applications.
IMPORTANT: The TCC will not engage until the engine is in closed loop operation and the vehicle speed is as shown in the Shift Speed table. Refer to Shift Speed (M30/M32/M70) or Shift Speed (M33 Only) . The vehicle must be in a near-cruise condition, not accelerating or coasting, and on a level road surface.
8. Check for TCC apply in THIRD and FOURTH gear.
   • Note the TCC apply point. When the TCC applies there should be a noticeable drop in engine speed and a drop in slip speed to below 100 RPM. If the TCC apply can not be detected:
     • Check for DTCs.
     • Refer to Torque Converter Diagnosis Procedure .
   • Refer to the Shift Speed (M30/M32/M70) or Shift Speed (M33 Only) table for the correct apply speeds.