Electrical Function Check

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 mis-diagnosed.

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 for typical data values. Data that is questionable may indicate a concern.
^ Engine speed
^ Transmission output speed
^ Vehicle speed
^ TFP manual valve position switch
^ Transmission range, engine list
^ 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 that 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 2-3 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 that 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.