Before On-Board Diagnostics

Before any diagnostic testing is done on a vehicle some preliminary checks must be performed, below. Be sure to write down your findings, especially any DTC, for future reference.

1. Know and Understand the customer's concern.
2. Verify customer's concern (when does it exist?)
a. upshift
b. downshift
c. coasting
d. engagement
e. noise/vibration
3. If noise/vibration, check for dependencies:
a. RPM dependent
b. vehicle speed dependent
c. shift dependent
d. gear dependent
e. range dependent
f. temperature dependent
4. Vehicle at normal operating temperature.
5. Check fluid level and condition.
6. Visually inspect the vehicle for the following items:
- vehicle modifications
- electronic add-on items
- leaks
- proper linkage adjustments
7. Check TSBs concern information.
8. Perform the COMPLETE On-Board Diagnostic procedures (KOEO, KOER).