GM Service Manual Online
For 1990-2009 cars only

Intelligent Switching Unit (ISU)

Door Switch: The scan tool displays Open or Closed. When a door is opened, the scan tool will display Open. When the door is closed, the scan tool will display Closed.

Driver Door Switch: The scan tool displays Released or Applied. When the driver door is open, the scan tool will display Released. When the driver door is closed, the scan tool will display Applied.

Hazard Lamp Switch : The scan tool displays On or Off. When the hazard switch is depressed, the scan tool will display On momentarily, then Off. When the switch is depressed again, the scan tool will again display On momentarily, then Off.

Hood Open Switch : The scan tool displays Active or Inactive. When the hood is open, the scan tool will display Active. When the hood is closed, the scan tool will display Inactive.

Ignition 1: The scan tool displays ON or OFF. When the ISU detects ignition 1 is present, the scan tool will display Yes. When the ISU does not detect ignition 1, the scan tool will display OFF.

Ignition 2 : The scan tool displays ON or OFF. When the ISU detects ignition 2 is present, the scan tool will display Yes. When the ISU does not detect ignition 2, the scan tool will display OFF.

Left Turn Signal Switch: The scan tool displays Active or Inactive. When the multi-function switch is pulled down, the scan tool will display Active. When the switch is in the normal condition, the scan tool will display Inactive.

Parking Lamps: The scan tool displays On or Off. When the lamp switch is in the Park or Head position, the scan tool will display On. When the switch is in the Off position, the scan tool will again display Off.

Right Turn Signal Switch: The scan tool displays Active or Inactive. When the multi-function switch is pushed up, the scan tool will display Active. When the switch is in the normal condition, the scan tool will display Inactive.

Tamper Status: The scan tool displays Active or Inactive. When a key tamper switch (door or trunk key cylinder) is locked or normal position, the scan tool will display Inactive. When the switch is unlocked, the scan tool will display Active.

Trunk Open Switch : The scan tool displays Open or Closed. When the hood is open, the scan tool will display Open. When the hood is closed, the scan tool will display Closed.