GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The purpose of the inspection maintenance (I/M) complete system set procedure is to satisfy the enabled criteria necessary to execute all of the I/M system monitors. When all system monitors are completed, the I/M system status indicators are set to YES. Perform this procedure when more than one of the I/M system status indicators are set to NO.

Conditions for Updating the I/M System Status

Each system monitor requires at least one, and sometimes several, diagnostic tests. The results of these tests are reported by a DTC. A system monitor completes when either all DTCs comprising the monitor have run and passed, or any DTC comprising the monitor has illuminated the malfunction indicator lamp (MIL). Once the monitor completes, the I/M system status display will indicate YES in the Completed column. For example, when the Misfire Monitoring System Status display indicates YES, all of the misfire components have been diagnosed. The I/M system status will indicate NO in the Completed column when any of the required DTCs for that system have not run. The following is a list of conditions that would set the I/M System Status indicators to NO:

    • The vehicle is new from the factory and has not yet been driven through the necessary drive conditions to complete the system monitor.
    • The battery has been disconnected or discharged below operating voltage.
    • The control module power or ground has been interrupted.
    • The control module has been reprogrammed.
    • The control module DTCs have been cleared as part of a service procedure.

Monitored Emission Control Systems

The OBD II system monitors all emission control systems that are on-board. Not all vehicles have a full complement of emission control systems. For example, a vehicle may not be equipped with exhaust gas recirculation (EGR). The OBD II regulations require monitoring of the following:

    • Comprehensive component monitoring--Emission related inputs and outputs
    • The EGR system
    • Misfire monitoring
    • Catalyst monitoring

For the specific DTCs required for each system, refer to Inspection/Maintenance (I/M) System DTC Table.

Circuit/System Verification

Review the I/M system status indicators. All I/M system status indictors should report YES.

Circuit/System Testing

Important: Any DTCs set, even those not listed in the I/M system DTC table, may prevent the required DTCs from running.

  1. Repair any DTCs or driveability concerns.
  2. Review any service bulletins for software updates that may prevent the required DTCs from running.
  3. Perform any reprogramming or repairs indicated by the service bulletins.
  4. If more than one system indicates a NO status or did not update to YES , refer to Inspection/Maintenance (I/M) Complete System Set Procedure.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.