System Readiness Test Codes: Description
System Readiness Test (SRT) code is specified in Mode 1 of SAE J1979. As part of an enhanced emissions test for Inspection and Maintenance (I/M), certain states require the status of SRT be used to indicate whether the ECM has completed self-diagnosis of major emission systems and components. Completion must be verified in order for the emissions inspection to proceed. If a vehicle is rejected for a State emissions inspection due to one or more SRT items indicating INCMP, use the following information to set the SRT to CMPLT. See Fig 1. In most cases the ECM will automatically complete its self-diagnosis cycle during normal usage, and the SRT status will indicate CMPLT (complete) for each application system. Once set as CMPLT, the SRT status remains CMPLT until the self-diagnosis memory is erased. Occasionally, certain portions of the self-diagnostic test may not be completed as a result of the customer's normal driving pattern; the SRT will indicate INCMP for these items.
The SRT will also indicate INCMP (incomplete) if the self-diagnosis memory is erased for any reason or if the ECM memory power supply is interrupted for several hours. If, during the state emissions inspection, the SRT indicates CMPLT for all test items, the inspector will continue with the emissions test. However, if the SRT indicates INCMP for one or more of the SRT items the vehicle is returned to the customer untested. If MIL is illuminated during the state emissions inspection, the vehicle is also returned to the customer untested even though the SRT indicates CMPLT for all test items. Therefore, it is important to check SRT (CMPLT) and DTC (NO DTCs) before the inspection.