GM Service Manual Online
For 1990-2009 cars only

The courtesy lamps come on and stay on for a set time whenever the interior lamp control is in the door position and the UNLOCK button on the Remote Keyless Entry (RKE) transmitter is pressed.

The lamps stay on while a door is opened and then turn off automatically about 25 seconds after it is closed. If the UNLOCK button is pressed and a door is not opened, the lamps will turn off after about 25 seconds.

The courtesy lamps turn off when the ignition key is turned to ON/RUN or START. They will come on again when a door is opened.