Road Test Procedure

Road Test Procedure
The following test provides a method of evaluating the condition of the automatic transmission. The test is structured so that most driving conditions would be achieved. The test is divided into the following parts:
^ Electrical Function Check
^ Upshift Control and Torque Converter Clutch (TCC) Apply
^ Part Throttle Detent Downshifts
^ Full Throttle Detent Downshifts
^ Manual Downshifts
^ Coasting Downshifts;
^ Manual Gear Range Selection
- REVERSE
- Manual FIRST
- Manual SECOND
- Manual THIRD

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

Before the road test, ensure the following:
^ The engine is performing properly.
^ Transmission fluid level is correct.
^ Tire pressure is correct.

During the road test:
^ Perform the test only when traffic conditions permit.
^ Operate the vehicle in a controlled, safe manner.
^ Observe all traffic regulations.
^ View the scan tool data while conducting this test. Take along qualified help in order to operate the vehicle safely.
^ Observe any unusual sounds or smells.

After the road test, check the following:
^ Transmission fluid level.
^ Diagnostic Trouble Codes (DTCs) that may have set during the testing. Refer to the applicable DTC.
^ Scan tool data for any abnormal readings or data.

Electrical Function Check
Perform this check first, in order to ensure the electronic transmission components are connected and functioning properly. If these components are not checked, a simple electrical condition could be misdiagnosis.
1. Connect the scan tool.
2. Ensure the gear selector is in PARK and set the parking brake.
3. Start the engine.
4. Verify that the following scan tool data can be obtained and is functioning properly.
Refer to Transmission Scan Tool Data List (Gas) or Transmission Scan Tool Data List (Diesel) for typical data values. Data that is questionable may indicate a concern.
^ Engine Speed
^ Transmission input speed (turbine)
^ Transmission output speed
^ Vehicle speed
^ TFP manual valve position switch
^ Transmission range (engine list)
^ 4WD low
^ Commanded gear (current gear)
^ PC solenoid reference current
^ PC solenoid actual current
^ PC solenoid duty cycle
^ Brake switch
^ Engine coolant temperature
^ Transmission fluid temperature
^ Throttle angle
^ Ignition voltage
^ 1-2 shift solenoid
^ 2-3 shift solenoid
^ TCC solenoid duty cycle
^ TCC slip speed

5. Monitor the brake switch signal while depressing and releasing the brake pedal. The scan tool should display:
^ Closed when the brake pedal is released
^ Open when the brake pedal is depressed

6. Check the garage shifts
6.1. Apply the brake pedal and ensure the parking brake is set.
6.2. Move the gear selector through the following ranges:
6.2.1. PARK to REVERSE
6.2.2. REVERSE to NEUTRAL
6.2.3. NEUTRAL to DRIVE

6.3. Pause 2 to 3 seconds in each gear position.
6.4. Verify the gear engagements are immediate and not harsh.

Important: Harsh engagement may be caused by any of the following conditions:
^ High idle speed. Compare engine idle speed to desired idle speed.
^ Commanded low PC solenoid current. Compare PC solenoid reference current to PC solenoid actual current.
^ A default condition caused by certain DTCs that result in maximum line pressure to prevent slippage. important: 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. Compare PC solenoid reference current to PC solenoid actual current.
^ Cold transmission fluid. Check for low transmission fluid temperature.

7. Monitor transmission range on the scan tool (engine list),
7.1. Apply the brake pedal and ensure the parking brake is set.
7.2. Move the gear selector through all ranges.
7.3. Pause 2 to 3 seconds in each range.
7.4. Return gear selector to PARK.
7.5. Verify that all selector positions match the scan tool display.

8. Check throttle angle input.
8.1. Apply the brake pedal and ensure the parking brake is set.
8.2. Ensure the gear selector is in PARK.
8.3. Monitor throttle angle while increasing and decreasing engine speed with the throttle pedal. The scan tool throttle angle 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.