Test AE: Left Seat Belt PRETENSIONER Circuit Short To Battery Or Ignition (DTC B1878): Description
WARNING: This page is about a different car, the 2002 Lincoln Blackwood. However, it is still accessible from the selected car via links, so may be relevant.
Restraints Control Module (RCM) monitors left seat belt pretensioner circuit voltage at connector C2041A, terminals No. 18 (Light Green/Red wire) and No. 22 (Light Green/Black wire). If RCM detects a short to battery or ignition, it will store Diagnostic Trouble Code (DTC) B1878 in memory and flash Code 17 on AIR BAG warning light.