Diagnostic Test Drive

Diagnostic Test Drive
When servicing vehicles, the vehicle antilock brake and traction control system, test drives will be necessary to allow all tests to be run, and all system functions to be enabled and exercised. A test drive may also be required to duplicate specific DTCs covered in this section. The diagnostic system check (including test drive) should be run when vehicle repairs are complete in order to verify the repair.
The diagnostic test drive will vary for ABS/TCS problems.
1. Read the Diagnostic Aids and the Conditions for Setting the DTC.
2. Reconnect any previously disconnected components.
3. Start the engine.
4. Drive the vehicle under the following conditions for at least 10 minutes. At no times should any unlawful or unsafe maneuvers be performed.
^ Highway driving.
^ Rough roads.
^ Verify customers concern and duplicate driving conditions.
^ With the engine still running use the scan tool and check for any DTCs. If any DTCs are set, perform the appropriate DTC table.

Diagnostic Strategy
In difficult diagnostic situations use the above information to identify malfunction occurrence trends.
Ask question such as the following:
^ Did the malfunction only occur once over a large number of drive cycles, indicating an unusual condition present when it occurred?
^ Does the malfunction occur infrequently over a large number of drive cycles, indicating that special diagnostic techniques may be required to identify the source of the malfunction?
A malfunction that occurs more frequently increases the odds of finding the cause of the malfunction.
Use the information in order to determine if a DTC is intermittent. Use the information in order to determine if the DTC has not set for long periods of time due to weather changes or a repair prior to this visit.