Volt

Road Test

Note: The Road Test Procedure should be performed only as part of the Symptom Diagnosis. Refer to Symptoms - Automatic Transmission .

The following test provides a method of evaluating the condition of the automatic transmission. The test is structured for two most common driving conditions, which are Electrically Variable Engine Off and Electrically Variable Engine On. The test is structured so that most driving conditions would be achieved. The test is divided into the following parts:

Note: Complete the test in the sequence given. Incomplete testing cannot guarantee an accurate evaluation.

Before the road test, ensure the following:

During the road test:

After the road test, check the following:

Perform this procedure first in order to ensure the electronic transmission components are functioning properly. If these components are not checked, a simple electrical condition could be misdiagnosed.

1. Connect the scan tool.
2. Ensure the gear selector is in PARK and set the parking brake.
3. Start the engine. To ensure the engine starts open the hood.

Note: Note that the engine may not start depending on the state of charge in the battery. For more information refer to Hybrid Modes of Operation Description .

4. Verify that the following scan tool data can be obtained and is functioning properly.

Refer to Transmission Control Module Scan Tool Information for typical data values. Data that is questionable may indicate cause for concern.

•	Engine Torque

•	Drvr Axle Torque Request

•	Calc. Throttle Position

•	Engine Speed

•	Calc. Trans Input Speed

•	Transmission OSS

•	ISS/OSS Supply Voltage

•	Replicated OSS CKT Status

•	Vehicle Speed

•	Output Shaft Direction

•	Variable Low 1-2R Clutch Slip

•	Variable High 2-3-4 Clutch Slip

•	4th Clutch Slip

•	1-3R Clutch Slip

•	Variable Low 1-2R Clutch Status

•	Variable High 2-3-4 Clutch Status

•	4th Clutch Status

•	1-3R Clutch Status

•

IAT

•	Brake Switch

•	Shift Solenoid 1

•	Shift Solenoid 2

•	Commanded Gear

•	Gear Ratio

•	Driver Shift Control

•	Driver Shift Request

•	IMS A/B/C/P

•

IMS

•	TFP Switch 1

•	TFP Switch 3

•	TFP Switch 4

•	TFP Switch 5

•

ECT

•	Trans. Fluid Temp.

•	TCM Power Up Temperature

•	TCM Temperature

•	PC Sol. 2 Pressure Cmd.

•	PC Sol. 3 Pressure Cmd.

•	PC Sol. 4 Pressure Cmd.

•	PC Sol. 5 Pressure Cmd.

•	Line PC Sol. Pressure Cmd.

•	Engine Run Time

•	EC Ignition Relay Feedback Signal

•	Ignition Voltage

•	Transfer Case Ratio

5. Check the garage shifts.

5.1.	Apply the brake pedal and ensure the handbrake is set.

5.2.	Move the gear selector through the following ranges:

5.2.1.

PARK to REVERSE

5.2.2.

REVERSE to NEUTRAL

5.2.3.

NEUTRAL to DRIVE

5.3.	Pause 2 to 3 seconds in each gear position.

5.4.	Verify the gear engagements are immediate and not harsh.

Note: These shifts can not be felt when trans is functioning properly.

Note: Harsh engagement may be caused by any of the following conditions:

•	High engine idle speed-Compare engine idle speed to desired idle speed.

•	Commanded low pressure control (PC) solenoid current--Investigate PC Sol. Pressure Cmd. kPa (psi) for all solenoids. High pressure will cause harsh shifts.

•	A default condition caused by certain DTCs that result in maximum line pressure to prevent clutch slippage.

Note: Soft or delayed engagement may be caused by any of the following conditions:

•	Low idle speed--Compare engine idle speed to desired idle speed

•	Low fluid level

•	Commanded high PC solenoid current--Investigate PC Sol. Pressure Cmd. kPa (psi) for all solenoids. Low pressure will cause soft or delayed shifts

•	Cold transmission fluid temperature (TFT)--Use the scan tool to determine TFT

•	Selector linkage--Inspect and adjust as necessary

6. Monitor transmission range on the scan tool, trans data list.

6.1.	Apply the brake pedal and ensure the handbrake is set.

6.2.	Move the gear selector through all ranges.

6.3.	Pause 2 to 3 seconds in each range.

6.4.	Return gear selector to PARK.

6.5.	Verify that all selector positions match the scan tool display.

7. Check throttle position input.

7.1.	Apply the brake pedal and ensure the handbrake is set.

7.2.	Ensure the gear selector is in PARK.

7.3.	Monitor the scan tool Calc. Throttle Position while increasing and decreasing engine speed with the throttle pedal. The scan tool Calc. Throttle Position percentage should increase and decrease with engine speed.

If any of the above checks do not perform properly, record the result for reference after completion of the road test.

The TCM calculates the ratio points based primarily on 2 inputs: throttle position and vehicle speed.

Note: If in the above steps you opened the hood to start the engine make sure it is closed before driving the vehicle.

Perform the following steps:

1. Choose a throttle position of 12.5 percent or 25 percent. All throttle positions shown should be tested to cover the normal driving range.
2. Monitor the following scan tool parameters:

•	Calc. Throttle Position

•	Vehicle Speed

•	Engine Speed

•	Transmission OSS

•	Commanded Gear

•	TFP Switch 1

•	TFP Switch 3

•	TFP Switch 4

•	TFP Switch 5

•	PC Sol. 2 Pressure Cmd.

•	PC Sol. 3 Pressure Cmd.

•	PC Sol. 4 Pressure Cmd.

•	PC Sol. 5 Pressure Cmd.

•	Shift Solenoid 1 and 2

3. Place the gear selector in the DRIVE position.
4. Accelerate the vehicle using the chosen throttle position. Hold the throttle steady.
5. As the vehicle accelerates, there should be a noticeable shift feel. The vehicle should be able to accelerate to the desired throttle position or speed with no noticeable problems.

Note any noise or vibration.

This range is used to slow the vehicle more when the driver's foot is lifted from the throttle. This range will feel like "engine braking" with the engine on or off.

Reverse

Perform the following test using a 10-15 percent throttle position.

1. With the vehicle stopped, move the gear selector to REVERSE.
2. Slowly accelerate the vehicle.
3. Verify that there is no noticeable slip, noise or vibration.