Initial Inspection and Diagnostic Overview

Before a road test, get a complete description of the customer concerns or suspected condition. From the description, the technician's experience will allow the technician to match possible causes with symptoms. Certain components will be tagged as possible suspects while others will be eliminated by the evidence. More importantly, the customer's description can reveal unsafe conditions which should be checked or corrected before the road test. The description will also help form the basic approach to the road test by narrowing the concern to specific components, vehicle speed or conditions.

Perform a road test to compare actual vehicle braking performance with the performance standards expected by the driver. The ability of the test driver to make valid comparisons and detect performance deficiencies will depend on experience.

If a concern exists, use the Brake System Symptom Chart to isolate it to a specific subsystem and condition description. From this description, a list of possible sources can be used to further narrow the cause to a specific component or condition.