Ford 3W1Z-12A650-AYB
PCM, Black Oak

The Flash Electrically Eraseable Programmable Read Only Memory (EEPROM) inside the Powertrain Control Module (PCM) stores both the vehicle strategy and vehicle-specific calibration data for multiple program or flash operations. To prevent fault codes P1635 and P1639 the Vehicle Identification (VID) block needs to be programmed when exchanging the PCM because it shows an unprogrammed VID block or damaged information in the block. Modification of the Vehicle Identification data can achieve correct hardware parameter adjustment after production but improper adjustments could trigger fault code P1635 then P1639 due to the Tire/Axle Ratio out of Acceptable Range. An essential portion of the VID block consists of important information including VIN number and octane adjust and fuel type and vehicle speed limit along with tire size and axle ratio and both speed control and four-wheel drive system presence data. Users must observe VID block range restrictions imposed by the strategy and must keep reprogramming under the specified maximum as exceeding the threshold triggers the scan tool to display the need for a PCM flash. The procedure to enter data into VID block consists of automatic data retrieval when the former PCM is functional but requires manual entry in case the old module needs replacing. Transfer of data from old PCM to new PCM becomes possible through automatic procedures when a scan tool extracts the data before removing the module. The correct programming of Tire Size and Axle Ratio together with shift type (Manual/Electronic shift on the fly) must be performed with a compatible scan tool after PCM replacement to prevent fault codes P1635 and P1639 from appearing. Tire Size needs to be calculated first by dividing 63,360 by inches of tire circumference. Technicians must seek information at the "AS BUILT" data center when the old PCM proves unutilizable or contains corrupted data. Ford technicians should contact their National Hotline or visit the Professional Technician Society (PTS) website and other parties can access information through the Fed World website for vehicle calibrations. The VID block requires modifications when updating vehicle hardware elements and total EEPROM reprogramming occurs due to both strategy or calibration modifications and VID block reset operations when reaching maximum reconfiguration numbers.