2009 Hummer H3T Owner's Manual - Page 148

3-30 Instrument Panel When the Light Flashes First and Then is On Steady This indicates that there may be a problem with the Tire Pressure Monitor System. The light flashes for about a minute and stays on steady for the remainder of the ignition cycle. This sequence will repeat with every ignition cycle. See Tire Pressure Monitor System on page 5-52 for more information. This light comes on when the ignition is on, but the engine is not running, as a check to show it is working. If it does not, have the vehicle serviced by your dealer/retailer. If the check engine light comes on and stays on, while the engine is running, this indicates that there is an OBD II problem and service is required. Malfunctions often are indicated by the system before any problem is apparent. Being aware of the light can prevent more serious damage to the vehicle. This system assists the service technician in correctly diagnosing any malfunction. Notice: If the vehicle is continually driven with this light on, after a while, the emission controls might not work as well, Tire Pressure Light The tire pressure light should come on briefly as the engine is started. If it does not, have the vehicle service by your dealer/retailer. It provides information about tire pressures and the Tire Pressure Monitoring System. When the Light is On Steady This indicates that one or more of the tires are significantly underinflated. A tire pressure message in the Driver Information Center (DIC), may accompany the light. See DIC Warnings and Messages on page 3-37 for more information. Stop and check the tires as soon as it is safe to do so. If underinflated, inflate to the proper pressure. See Tires on page 5-44 for more information. Malfunction Indicator Lamp Check Engine Light A computer system called OBD II (On-Board Diagnostics-Second Generation) monitors operation of the fuel, ignition, and emission control systems. It ensures that emissions are at acceptable levels for the life of the vehicle, helping to produce a cleaner environment.