AIR BAG - DIAGNOSTIC TROUBLE CODE (DTC) 12 AND OR 52
RESTRAINT SYSTEM - AIR BAG SYSTEM DIAGNOSTIC TROUBLE CODE (DTC) 12 AND OR 52
Publication Date: APRIL 20, 1994
Customers may experience air bag system Diagnostic Trouble Code (DTC) 12 and/or 52 on some vehicles. This may be caused by the Air Bag Diagnostic Monitor, which contains non-volatile memory (NVM). NVM cannot be cleared by cycling the ignition key or by disconnecting the battery.
Refer to the appropriate vehicle Service Manual, Section 01-20B for diagnostic procedures. Repair any concern which exists and clear the codes from NVM as outlined in the following article.
The all-new air bag diagnostic monitor for the 1994 Mustang and the 1995 Windstar vehicles contains Non-Volatile Memory (NVM). After a concern has been repaired, the appropriate DTC must be cleared from NVM.
Beginning 1/14/94, a change was made to the memory program of the air bag diagnostic monitor of the Mustang vehicle:
1994 Mustang vehicles built before 1/14/94 - A low battery (battery below 8 volts) may set a DTC 12, which may be logged in NVM. Upon restoration of the battery above 8 volts, a DTC 52 will be indicated. The DTC 52 may be cleared by using the clearing procedure in the 1994 Service Manual, Section 01-20B.
1994 Mustang vehicles built on or after 1/14/94, and All Windstar Vehicles - A low battery (battery below 8 volts) may set a DTC 12. However, the DTC 12 will not be written to NVM. Therefore, upon restoration of the battery above 8 volts, DTC 52 will not be indicated. In these vehicles, a DTC 52 will ONLY be indicated if the dedicated air bag fuse circuit was open and is presently repaired, or is intermittent.
CLEARING THE DTC's
Use the following procedure to clear DTC's from NVM:
Follow the diagnostic procedures to repair the condition flashing on the air bag indicator.
Cycle the ignition key to OFF and then to RUN.
Observe air bag indicator prove out (6 ± 2 seconds), followed by DTC (52-85) flashing completely one time
Locate the diagnostic service connector containing circuits 631 (T/R) and 57 (BK). This is a gray connector under the glove box in Mustang and above the accelerator pedal in Windstar.
Use a jumper wire to short circuit 631 (T/R) to circuit 57 (BK) or to another good ground.
Hold short until diagnostic monitor tone sounds (approximately five (5) seconds.)
Release short on circuit 631 (T/R) to circuit 57 (BK).
The DTC is now cleared. The next highest priority concern code stored in NVM (if one exists) will begin flashing. Repeat if necessary.
An Engineering support toll-free number has been established for the Mustang and Windstar air bag systems: 1-800-AIRBAG8 (1-800-247-2248). Please call this number before replacing the air bag diagnostic monitor.