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linb
New User
Nov 7, 2008, 5:34 AM
Post #1 of 2
(3694 views)
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J have a 94 Grand Marquis that has an airbag code 51 that is flashing and would like to know how to fix this myself. Thanks!
(This post was edited by linb on Nov 7, 2008, 5:35 AM)
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way2old
Veteran
/ Moderator
Nov 7, 2008, 5:47 AM
Post #2 of 2
(3688 views)
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Re: Airbag Code 51
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The following is from the service manual. It is for the LFC 51 if the air bag has not been deployed. There is a short to ground somewhere that has blown the internal fuse in the diagnostic monitor. You need to repair the short before you replace the monitor. There is a wiring schematic below to help you also..
Diagnostic Trouble Code 51
Diagnostic Monitor Internal Thermal Fuse—Fuse Blown Due to Intermittent Short to Ground
Short to Ground Was Serviced or Is Intermittent
Normal Operation
NOTE: The air bag diagnostic monitor contains an internal thermal fuse that is not serviceable. The thermal fuse is controlled by the air bag diagnostic monitor . The air bag diagnostic monitor will blow its thermal fuse whenever a short on the deployment circuits occurs. The thermal fuse does not blow because of excessive current flowing through it. DO NOT attempt to short circuit the thermal fuse with a circuit breaker or any other type of fuse.
 WARNING: DO NOT INSTALL A NEW AIR BAG DIAGNOSTIC MONITOR UNTIL THE SHORT HAS BEEN LOCATED AND CORRECTED. IF A SHORT TO GROUND HAS NOT BEEN LOCATED AND CORRECTED, THEN THE SHORT TO GROUND IS INTERMITTENT AND IS NOT PRESENT AT THIS TIME. INSTALLING A NEW AIR BAG DIAGNOSTIC MONITOR WITH AN INTERMITTENT SHORT IN THE SYSTEM WILL RESULT IN REPEAT BLOWN AIR BAG DIAGNOSTIC MONITOR THERMAL FUSE AND REPEAT SERVICE.
The air bag diagnostic monitor measures the voltages at the air bag diagnostic monitor connector pins. When certain air bag deployment wires are shorted to ground (heavy lines illustrated in the schematic), the system may become susceptible to unwanted deployment of the air bags. The air bag diagnostic monitor senses a short to ground on any of these circuits and helps prevent unwanted air bag deployment by blowing the air bag diagnostic monitor thermal fuse. Blowing this fuse removes all power (battery and backup power) from the air bag deployment circuits. While the short to ground exists, the air bag diagnostic monitor will flash diagnostic trouble code 13. If the short to ground is intermittent and temporarily corrects itself, the air bag diagnostic monitor will flash diagnostic trouble code 51.
NOTE: If the short to ground returns, the higher priority diagnostic trouble code 13 will flash instead of 51.
If the air bag warning indicator is flashing diagnostic trouble code 51 and a short to ground has not been serviced, this means that an intermittent short to ground exists in the air bag system. The air bag diagnostic monitor should be replaced only after service to the intermittent short has been completed.
Some service tips for finding an intermittent short to ground are: - Consult OASIS (Restraint Systems Service Code 104000) for up to date diagnostics and descriptions of wiring concern locations for the vehicle (VIN number) you are working on. OASIS is updated daily using concern descriptions from engineering and Dealership Service sources.
- Inspect wiring and harnesses in areas where they pass through or are located next to metal components (i.e. engine compartment bulkhead, body sheet metal, component mounting brackets, etc).
Being way2old is why I need help from younger minds
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