Preliminary Inspection

Before any diagnostic testing is done on vehicle some preliminary checks must be performed, as described below. Be sure to write down findings, especially any DTCs found, for future reference.
a. Check transmission fluid level and condition.
b. Check for add-on items (phones, computers, CB radio, etc.).
c. Visually inspect wiring harness and connectors.
d. Check for vehicle modifications.
e. Check shift linkage for proper adjustment.
f. Verify customer concern: upshift, downshift, coasting, engagement, noise/vibration
g. Vehicle must be at normal operating temperature.
h. Perform vehicle on-board diagnostic.
i. Record all DTCs.
j. Service all non-transmission codes.