Ford BA8Z-12A650-LD
PCM

The Engine Control Module (ECM) uses an Electrically Erasable Programmable Read Only Memory (EEPROM) that exists inside the powertrain control module (PCM) to store vehicle-specific calibration data for programming or flashing multiple times. A new PCM needs a programmed vehicle identification (VID) block because a lack of this step leads to possible diagnostic trouble codes (DTC) P1635 or P1639. Making improper changes to the VID block since production might activate DTC P1635 or reveal an incorrect tire/axle ratio which stands as a typical DTC P1639 cause. Among essential VIN information in the VID block stands the vehicle identification number (VIN), alongside octane adjust, fuel type, vehicle speed limit, tire size, axle ratio and speed control versus electronic shift-on-the-fly (ESOF) and manual shift-on-the-fly (MSOF). The range limits on tire and axle ratios exist within the VID block so a notification will appear when the reconfiguration limit reaches its threshold prior to requiring PCM flash procedure. To activate misfire monitor functionality on vehicles with DTC permanent reporting, technicians must perform learning of the neutral profile after PCM replacement through the Misfire Monitor Neutral Profile Learn function available on the scan tool. The learning process must be performed whenever there is a PCM or crankshaft position (CKP) sensor change or major engine work takes place. The verification of neutral profile learning completion requires an inspection of the MP LRN PID with a scan tool which should display YES after completion. The VID block of a new PCM contains no programmed data so it must be populated either by transferring data from another PCM or by manual data entry because of PCM damage. The process requires a suitable scan tool to enter parameters which must include accurate tire information at revolutions per mile together with axle ratio and 4x4/4x2 settings to prevent the appearance of DTCs P1635 and P1639. The As-Built Data Center should be contacted by technicians for manual updates when either old PCM is undependable or data is inaccessible. Ford and Lincoln Mercury service center technicians obtain As-Built data through the National Hotline or PTS website although non-Ford technicians benefit from Motorcraft® website access. Alterations to the VID block must occur to match vehicle hardware and full EEPROM reprogramming is essential when implementing strategy or calibration updates or when resetting the VID block because of its maximum usage requirement.