Test P: Air Bag Tone Warning Indicator Circuit Short To Battery Or Ignition (B1891): Description
WARNING: This page is about a different car, the 2003 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.
Restraints Control Module (RCM) monitors its connection to Generic Electronic Module (GEM) at RCM connector terminal No. 26 (Light Blue/Black wire). This connection is used to signal a chime if AIR BAG warning light is inoperative and another air bag system fault exists. If RCM detects a short to battery or ignition in connection to GEM, it will store Diagnostic Trouble Code (DTC) B1891 in memory.