Upshift Control and Torque Converter Clutch (TCC) Apply

The vehicle computer calculates the upshift points based primarily upon two inputs:
- Throttle angle
- Vehicle speed
When the PCM indicates that a shift should occur, an electrical signal is sent to the shift solenoids, which in turn move the valves to perform the upshift.

The shift speed charts refer to THROTTLE ANGLE instead of MIN THROTTLE or WOT in order to make shift speed measurement more uniform and accurate. Monitor THROTTLE ANGLE by using the scan tool.

Some scan tools have been programmed in order to measure and record shift point information. Check the instruction manual in order to see if this test is available.

With gear selector in D4, perform the following steps:
1. Refer to SHIFT SPEED and choose a throttle position of either 15% or 20%.
2. Monitor the throttle position with the scan tool.
3. Accelerate to the chosen throttle position. Hold the throttle steady.

Important: Shift speeds may vary due to slight hydraulic delays in responding to electronic controls. A change from the original equipment tire size also affects shift speeds.

4. As the transmission upshifts, note the shift speed for each of the following gears:
- 2nd gear
- 3rd gear
- 4th gear
5. The Torque Converter Clutch (TCC) should apply in Third or Fourth gear. The TCC will not apply unless the engine coolant has reached a minimum operating temperature of approximately 54° C (130° F). Note when the TCC applies. If you do not notice the apply by an RPM drop, refer to TORQUE CONVERTER CLUTCH DIAGNOSIS. Torque Converter Clutch Diagnosis
6. Repeat steps 1-5 using several different throttle angles.