Flash Electrically Erasable Programmable Read Only Memory

The Flash Electrically Erasable Programmable Read Only Memory (EEPROM) is an Integrated Circuit (IC) within the PCM. This IC contains the software code required by the PCM to control the powertrain. One feature of the EEPROM is that it can be electrically erased and then reprogrammed without removing the PCM from the vehicle.

Manual data entry must be performed if the old module is damaged and/or incapable of communicating. Remove and replace the old PCM. Using the WDS or equivalent tester, select and execute Module/Parameter reprogramming referring to the manufacturers users manual. Important, make certain that all parameters are included. Failure to properly program Tire Size in revolutions per mile, (rev/mile = 63,360 divided by the tire circumference in inches) Axle Ratio, 4x4/4x2, and/or Manual/Electronic shift on the fly (MSOF/ESOF) may result in codes: P1635, P1639.