2010 GMC Sierra 1500 Crew Cab Owner's Manual - Page 268

If none of the above have made the light turn off, your dealer can check the vehicle. The dealer has the proper test equipment and diagnostic tools to fix any mechanical or electrical problems that might have developed. The vehicle may not pass inspection if: . the check engine light is on with the engine running, or if the light does not come on when the ignition is turned to ON/RUN while the engine is off. the critical emission control systems have not been completely diagnosed by the system. This can happen if the battery has recently been replaced or if the battery has run down. The diagnostic system evaluates critical emission control systems during normal driving. This can take several days of routine driving. If this has been done and the vehicle still does not pass the inspection, your dealer can prepare the vehicle for inspection. Emissions Inspection and Maintenance Programs Some state/provincial and local governments may have programs to inspect the on-vehicle emission control equipment For the inspection, the emission system test equipment is connected to the vehicle's Data Link Connector (DLC). . The DLC is under the instrument panel to the left of the steering wheel. See your dealer if assistance is needed. 4-44