Electrical Function Check

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 selector lever is in PARK and set the parking brake.
3. Start the engine.
4. Verify that scan tool data can be obtained. Refer to Control Module References for typical data values. Data that is questionable may indicate a concern.
5. Monitor the TCC brake switch parameter while applying and releasing the brake pedal. The scan tool should display:
   • Open when the brake pedal is applied.
   • Closed when the brake pedal is released.
6. Check the garage shifts.
   • Apply the brake pedal and ensure the parking brake is set.
   • Move the gear selector through the following ranges:
     • PARK to REVERSE
     • REVERSE to NEUTRAL
     • NEUTRAL to DRIVE
   • Pause 2 to 3 seconds in each shift position.
   • Verify the gear engagements are immediate and not harsh.
     NOTE:

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

     • Verify the gear engagements are immediate and not harsh.
     • High engine idle speed - Compare engine idle speed to desired idle speed.
     • 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.
     • 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.
7. Monitor transmission range on the scan tool, engine data list.
   • Apply the brake pedal and ensure the parking brake is set.
   • Move the gear selector through all ranges.
   • Pause 2 to 3 seconds in each range.
   • Return gear selector to PARK.
   • Verify that all selector positions match the scan tool display.
8. Check throttle position input.
   • Apply the brake pedal and ensure the parking brake is set.
   • Ensure the selector lever is in PARK.
   • 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.