Before On-Board Diagnostics

Before any diagnostic testing is done on the vehicle, some preliminary checks must be performed. Be sure to write down any results, especially Diagnostic Trouble Codes (DTCs) retrieved, for future reference.
1. Check the Automatic Transmission Fluid (ATF) level and condition. Correct as necessary.
2. Visually inspect wiring harness and connectors.
3. Check for any vehicle modifications.
4. Check shift linkage for proper adjustment.
5. Verify the customer concern:
- Upshift.
- Downshift.
- Coasting.
- Engagement.
- Noise/Vibration.

6. Vehicle must be at normal operating temperature.
7. Perform vehicle On-Board Diagnostic (OBD) using New Generation Star (NGS) Tester.
8. Retrieve and record all DTCs.
9. Diagnose and repair all non-transmission DTCs before proceeding with any transmission diagnostics.