Perform a preliminary test before the road test in order to ensure that the electronic control inputs are operating properly. If you do not check the inputs before operating the transmission, you could misdiagnose a simple electrical condition as a major transmission condition.

A scan tool provides valuable information and must be used on the VT25-E transaxle for accurate diagnosis.

1. Ensure that the gear selector is in PARK (P) and set the parking brake.
2. Install the scan tool.
3. Start the engine.
4. Using the scan tool, the Transmission Scan Tool Data Definitions and the Transmission Scan Tool Data List, verify that the data parameters listed are present and functioning properly. Refer to Scan Tool Data Definitions and Scan Tool Data List .

The TCM calculates the speed ratio using two primary inputs: transaxle input speed and output speed. When the TCM demands an increase in the speed ratio, an electrical signal is sent to the ratio control motor to move the ratio control valve. The lever on the variable ratio control valve pulls the valve into a position which allows fluid from line 1 to enter the primary feed circuit. The primary feed fluid is routed to the apply piston cavities and the fluid pressure moves the piston side of the pulley toward the stationary half of the pulley. The drive belt reacts to the drive pulley position change by rising between the two sides of the pulley. Ratio changes begin as soon as the drive belt moves higher between the driver pulley halves.

Perform the road test using the scan tool.

Perform this test when traffic and road conditions permit. Observe all safety regulations.

1. Install the scan tool.
2. Start the engine.
3. Depress the brake pedal. Move the gear selector as follows:

•	PARK to REVERSE

•	REVERSE to NEUTRAL

•	NEUTRAL to DRIVE

•	The range engagement should be immediate and not harsh.

4. Set up the scan tool to monitor the Throttle Angle, Transmission Output Speed and Speed Ratio.
5. With the gear selector in DRIVE (D), accelerate to a chosen throttle angle and hold the throttle steady. Compare the output speed and speed ratio to a chosen throttle angle. Refer to Ratio Versus Speed - Ratio From Stop.
6. Repeat step 5. Refer to Ratio Versus Speed - Ratio Steady State.
7. Monitor the scan tool TCC Enable Solenoid parameter and accelerate to a chosen throttle angle. The TCC Enable Solenoid should activate at a transmission output speed of 500 RPM or greater.
8. Coasting down, the TCC Enable Solenoid should de-activate at a transmission output speed of 500 RPM or less.
9. Repeat steps 5-8 using different throttle angles.