Test C: Air Bag Warning Light Circuit Short To Battery (DTC B1870): Description
WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. However, it is still accessible from the selected car via links, so may be relevant.
AIR BAG warning light is designed to illuminate for 6 seconds when ignition switch is turned to ON position. The initial 6-second illumination is normal and is call prove-out. The AIR BAG warning light is then used to warn vehicle operator that there is a fault in the air bag system.
Restraints Control Module (RCM) monitors AIR BAG warning light for short to battery voltage conditions. If RCM detects short to battery voltage in AIR BAG warning light circuit, it will store DTC B1870 in memory. If RCM detects AIR BAG warning light failure in addition to another air bag system failure, the secondary air bag warning chime will be activated.