Upshift Control and TCC Apply

The PCM calculates the upshift points based primarily on two inputs: THROTTLE ANGLE and VEHICLE SPEED. When the PCM says a shift should occur, an electrical signal goes to the shift solenoids which in turn move the valves to perform the upshift.

The shift speed charts reference the THROTTLE ANGLE instead of MIN THROTTLE or WOT in order to make the shift speed measurement more uniform and accurate. Use a scan tool in order to monitor the THROTTLE ANGLE. Some scan tools are programmed in order to record shift point information. Check the instruction manual in order to see if this test is available.

With the gear selection in D4, do the following:
1. Look at the shift speed chart and choose a percent throttle angle of 15 or 20.
2. Set up the scan tool in order to monitor the THROTTLE ANGLE and the VEHICLE SPEED.
3. Accelerate to the chosen throttle angle and hold the throttle steady.

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

Note when the TCC applies. This should occur in third or fourth gear. If the apply is not noticed by an ROM drop, refer to the Preliminary Torque Converter Clutch diagnosis.

The TCC should not apply unless the transmission has reached a minimum operating temperature of 18° C (64° F) TRAN TEMP and an engine coolant temperature of 60° C (140° F).

4. As the transmission upshifts, note the shift speed and the commanded gear changes for the following:
- 2nd gear
- 3rd gear
- 4th gear

5. Repeat steps 1-4, using several different throttle angles.