2010 Cadillac STS Owner's Manual - Page 237

If, after several seconds, both status indicator lights remain on, or if there are no lights at all, there may be a problem with the lights or the passenger sensing system. See your dealer/retailer for service. Charging System Light This light comes on briefly when the ignition key is turned to START, but the engine is not running, as a check to show it is working. { WARNING: If the airbag readiness light in the instrument panel cluster ever comes on and stays on, it means that something may be wrong with the airbag system. If this ever happens, have the vehicle serviced promptly, because an adult-size person sitting in the right front passenger's seat may not have the protection of the airbag(s). See Airbag Readiness Light on page 4‑54 for more on this, including important safety information. If it does not, have the vehicle serviced by your dealer/retailer. The light should go out once the engine starts. If it stays on, or comes on while driving, there could be a problem with the charging system. A charging system message in the Driver Information Center (DIC) can also appear. See DIC Warnings and Messages on page 4‑76 for more information. This light could indicate that there are problems with a generator drive belt, or that there is an electrical problem. Have it checked right away. If the vehicle must be driven a short distance with the light on, turn off accessories, such as the radio and air conditioner. 4-57