M3.3 & M3.3.1 Engine Control Modules

As later versions of engine control modules (M3.3 & M3.3.1) were introduced it was not always necessary to replace the EPROM in order to perform an update to the module. The EPROMs installed on the newer systems are larger and allow additional information to be loaded without having to install a new EPROM. In the event that the size of the update exceeds the space available on the installed EPROM or an update was previously performed, then the installed EPROM will need to be replaced.

THE UPDATE CANCELS THE OLD FUNCTIONS CHARACTERISTICS AND ADDS THE UPDATED FUNCTION TO THE EPROM

Fig 1: Identifying EPROM Before Update

Courtesy of BMW OF NORTH AMERICA, INC.

Fig 2: Identifying EPROM After Update

Courtesy of BMW OF NORTH AMERICA, INC.

For the M3.3 & M3.3.1 systems the replacement EPROM that is installed does not contain all the data necessary for the engine to operate, it is a "basic" EPROM that only contains some basic data referred to as "resident data" which helps identify the module and allows the diagnostic equipment to determine what program and associated data needs to be installed/loaded.