Initial Inspection and Diagnostic Overview

How to Perform Trouble Diagnosis

BASIC CONCEPT
^ To perform trouble diagnosis, it is the most important to have understanding about vehicle systems (control and mechanism) thoroughly.





^ It is also important to clarify customer complaints before inspection.
First of all, reproduce symptoms, and understand them fully.
Ask customer about his/her complaints carefully. In some cases, it will be necessary to check symptoms by driving vehicle with customer.

CAUTION: Customers are not professional. It is dangerous to make an easy guess like "maybe the customer means that...," or "maybe the customer mentions this symptom".





^ It is essential to check symptoms right from the beginning in order to repair malfunctions completely.
For intermittent malfunctions, reproduce symptoms based on interview with customer and past examples. Do not perform inspection on ad hoc basis. Most intermittent malfunctions are caused by poor contacts. In this case, it will be effective to shake suspected harness or connector by hand. When repairing without any symptom diagnosis, you cannot judge if malfunctions have actually been eliminated.
^ After completing diagnosis, always erase diagnostic memory. Refer to TF-39, "ERASE SELF-DIAGNOSIS". Without Scan Tool
^ For intermittent malfunctions, move harness or harness connector by hand. Then check for poor contact or reproduced open circuit.