The strategy-based diagnostic is a uniform approach to repair all electrical/electronic
(E/E) systems. The diagnostic flow can always be used to resolve an E/E system problem
and is a starting point when repairs are necessary. The following steps will instruct
the technician on how to proceed with a diagnosis.
Verify the customer complaint. To verify the customer complaint, the technician
should know the normal operation of the system.
Perform preliminary inspections as follows:
| • | Conduct a thorough visual inspection. |
| • | Review the service history. |
| • | Detect unusual sounds or odors. |
| • | Gather diagnostic trouble code (DTC) information to achieve an effective
repair. |
| • | Check bulletins and other service information. This includes
videos, newsletters, etc. |
| • | Refer to service information (manual) system inspections. |
| • | Refer to service diagnostics. |
No Trouble Found
This condition exists when the vehicle is found to operate normally. The condition
described by the customer may be normal. Verify the customer complaint against another
vehicle that is operating normally. The condition may be intermittent. Verify the
complaint under the conditions described by the customer before releasing the vehicle.
Re-examine the complaints.
When the complaints cannot be successfully found or isolated, a re-evaluation
is necessary. The complaint should be re-verified and could be intermittent as defined
in intermittents, or could be normal.
After isolating the cause, the repairs should be made. Validate for proper operation
and verify that the symptom has been corrected. This may involve road testing or other
methods to verify that the complaint has resolved under following conditions:
| • | Conditions noted by the customer |
| • | If a DTC was diagnosed, verify the repair by duplicating conditions present
when the DTC was set as noted in Failure Records or Freeze Frame data. |
Verifying Vehicle Repair
Important: Follow the steps below when you verify repairs
on EOBD systems. Failure to follow these steps could result in unnecessary repairs.
Verification of the vehicle repair will be more comprehensive for vehicles with
Euro On-Board Diagnostic (EOBD) system diagnostics. Following a repair, the technician
should perform the following steps:
| • | Review and record the Failure Records and the Freeze Frame data for the
DTC which has been diagnosed. Freeze Fame data will only be stored for an A, B, and
E type diagnostic and only if the malfunction indicator lamp has been requested. |
| • | Operate the vehicle within conditions noted in the Failure Records and
Freeze Frame data. |
| • | Monitor the DTC status information for the specific DTC which has been
diagnosed until the diagnostic test associated with that DTC runs. |
