Normal Operation
WARNING: This page is about a different car, the 2007 Ford Pickup, 2007 Ford F550 Super Duty, 2007 Ford F450 Super Duty, and 2007 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
The restraints control module (RCM) monitors the status of the passenger air bag deactivation (PAD) switch at pin C2041 pin 8, circuit 1112 (WH/LB). The PAD switch signals the RCM by switching a resistance to ground. If the RCM senses 900-1100 ohms in the PAD switch, it enables the passenger air bag and turns off the PAD switch warning lamp. If the RCM senses 400-600 ohms in the PAD switch, it deactivates the passenger air bag and turns the PAD switch warning lamp on. If the RCM detects an invalid resistance, it will store a diagnostic trouble code (DTC) B1871 in memory and flash a lamp fault code (LFC) 25 (or higher priority code if one exists) on the air bag indicator.