This TSB is designed to aid the technician in diagnosing the following concerns:
Key Code Erase Procedure
Diagnostic Code U1147
False Diagnostic Code B1681
Refer to the following text if any of these concerns are present.
KEY CODE ERASE PROCEDURE
The Passive Anti-Theft System (PATS) is being offered starting with the 1996 model year vehicles listed. To perform a key code erase procedure, a New Generation Star Tester (NGS) software card, version 8.0 or higher, must be used. The key code erase procedure remains the same in all software versions. If an NGS tester is not available, an alternative method is provided in your Service Manuals.
Location of Procedures
Version 7.0 or earlier, the procedure is not available
Version 8.0, the procedure is located under the Active Command Modes Menu
Version 9.0 and higher, the procedure is located under the Function Tests Menu
DIAGNOSTIC CODE U1147
The Service Manual for the PATS/PCM may not provide enough information to properly diagnose a Code U1147. The fault code is logged when the PATS control module is not receiving the correct SCP messages from the Powertrain Control Module (PCM). In addition to receiving this fault code, a technician may determine this fault code by observing the theft LED located in the instrument panel when the key is in the RUN/START position. In this condition, the theft LED will glow for 2 seconds, turn off for 1 second, flash for 1 minute, then flash a fault code 1-6 (10 times).
If the vehicle exhibits this concern and the vehicle starts, there is a problem with the PCM. Determine if the PCM is in HLOS mode or has the correct level of calibration.
If the vehicle exhibits this condition and the vehicle does not start, there is no communication occurring between the PATS control module and the PCM. Check if a diagonstic tester can communicate with the PCM. If not, then check SCP (Circuits 914 and 915) link and module (power, grd...). If yes, then check for correct calibration or for diagnostic communication to the PATS control module.
FALSE DIAGNOSTIC CODE B1681
This concern is for the 1996 Taurus/Sable 3.0L 4V and SHO vehicles built on March 25-26, 1996 and 1996 Mustang GT and Cobra vehicles built from March 19-25, 1996.
New PATS transceiver modules were installed that may cause a false diagnostic code B1681 to be stored when an On-Demand Self Test is run. The code leads you to believe that there is a faulty transceiver module. Before replacing the transceiver module, make sure the pinpoint test is followed exactly to be sure the module is at fault. Retrieve and pursue all other diagnostic codes in the PATS control module memory (non-self test) before approaching the B1681 fault code in these vehicles.