Ignition Key In Signal: Description and Operation

Ignition key light operation (if equipped)
When any door is opened, grounding pin 20 of the electronic time and alarm control module, and there is no key inserted in the ignition switch, the control module will turn on the ignition key light. This light will remain illuminated for about 25 seconds or until the key is inserted into the ignition.

"Key in ignition" warning chime
When the key is inserted into the ignition switch, the key in ignition switch closes, applying battery voltage to pin 18 of the electronic time and alarm control module. If battery voltage is present at pin 18 and simultaneously a door is opened, grounding pin 20, the warning chime will sound, alerting the driver that the key is left in the ignition.