AIR BAG RESTRAINT SYSTEM -1993 Lincoln Town Car
NOTE: Before proceeding, After servicing has been performed, recheck AIR BAG warning light for codes with Air Bag Simulator (105-00010) still in place of air bag module. If system is okay, install air bag module and reactivate air bag system.
NOTE: A thermal fuse is built into diagnostic monitor. If a short to ground should occur in air bag deployment circuit, microcomputer in diagnostic monitor will send a signal to fuse, causing it to open. Open fuse removes all firing power (battery/back-up power) from deployment circuits. This prevents unwanted air bag deployments due to damaged vehicle wiring
CAUTION:Never replace diagnostic monitor without first determining cause for Code 51. If short to ground is not properly serviced, short may reoccur, once again destroying diagnostic monitor thermal fuse.
NOTE: Code 51 is displayed when diagnostic monitor thermal fuse is open and no higher priority faults exist. Code 51 is normally seen after service of Code 13 or 14. If Code 51 exists and Code 13 or 14 has not been serviced, an intermittent short to ground exists in air bag deployment wiring. Intermittent short to ground must be located and serviced before servicing Code 51.
CODE 51, DIAGNOSTIC MONITOR INTERNAL THERMAL FUSE OPEN
Diagnostic monitor measures voltages at diagnostic monitor terminals. When certain air bag deployment wires are shorted to ground, system may become susceptible to unwanted deployment of air bag. Diagnostic monitor senses a short to ground and helps prevent unwanted air bag deployment by blowing diagnostic monitor thermal fuse. Blowing this fuse removes all power (battery and back-up power) from air bag deployment circuits. If short to ground exists, diagnostic monitor will flash Code 13 or 14. If short to ground is intermittent and temporarily corrects itself, Code 51 will flash. If short to ground returns, Code 13 or 14 will flash instead of Code 51. If Code 51 is flashing and short to ground has not been repaired, an intermittent short to ground exists in air bag circuit. DO NOT replace diagnostic monitor until short to ground has been located and repaired.
Code 51 will set if there is a short to ground in circuit No. 614, 615, 616, 617, 619, 623, 624 or 625. A deployed air bag may also cause a Code 51 to set. When air bag deploys, internal wiring of air bag may become shorted to metal housing inside of air bag.
Check For Short To Ground
Inspect circuits No. 614, 615, 616, 617, 619, 623, 624 and 625 for short to ground. Inspect wiring harness areas where wires pass through or are located next to metal components. Repair as necessary.
Friday, April 3rd, 2009 AT 6:04 AM