GM Service Manual Online
For 1990-2009 cars only

The entry lighting system turns on the reading and dome lamps and the backlighting to the exterior lamp control, when a door is opened or if the Remote Keyless Entry (RKE) transmitter unlock button is pressed. If activated by the (RKE), the lighting stays on for about 25 seconds. The entry lighting system uses the light sensor on the instrument panel; so it must be dark outside in order for the lamps to turn on. The lamps turn off about 25 seconds after the last door is closed. They dim then turn off if the ignition key is turned to ON. They immediately turn off if the power locks are used.