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 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 CONTROL MODULE REFERENCES for typical data values. Data that is questionable may indicate a concern.

   • Engine Speed
   • Transmission ISS
   • Transmission OSS
   • Vehicle Speed
   • IMS
   • Commanded Gear
   • Gear Ratio
   • Line PC Sol. Pressure Cmd.
   • TCC Brake Switch
   • ECT, Engine Data List
   • Trans. Fluid Temp.
   • TCM Temperature
   • Calc. Throttle Position
   • Ignition Voltage
   • 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
   • Shift Solenoid 2
   • TCC PC Sol. Duty Cycle
   • TCC Slip Speed
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.
   1. Apply the brake pedal and ensure the parking brake is set.
   2. Move the gear selector through the following ranges:
      1. PARK to REVERSE
      2. REVERSE to NEUTRAL
      3. NEUTRAL to DRIVE
   3. Pause 2 to 3 seconds in each gear position.
   4. Verify the gear engagements are immediate and not harsh.
   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.
7. Monitor transmission range on the scan tool, engine data list.
   1. Apply the brake pedal and ensure the parking brake is set.
   2. Move the gear selector through all ranges.
   3. Pause 2 to 3 seconds in each range.
   4. Return gear selector to PARK.
   5. Verify that all selector positions match the scan tool display.
8. Check throttle position input.
   1. Apply the brake pedal and ensure the parking brake is set.
   2. Ensure the gear selector is in PARK.
   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.