EEPROM (Electrically Erasable Programmable Read Only Memory)
An EEPROM is a soldered in chip which is not removable from the control module. As their name Soldered in EEPROM implies, EEPROMS can be electrically erased and reprogrammed without opening the control module. This is known as "Flash Programming".
In either case, the E or EE PROM stores the loaded program data including
Scheme 110
- Characteristic maps for; Ignition, Injection, Purge control, etc...
- Characteristic curves.
- Control constants.
Coding selects a set of instructions that are already present in a control module. When a codable module is ordered from the parts department it contains all of the programs necessary for any applicable vehicle version.
The programs are stored in an EPROM as "Resident Data". During the coding process one set of instructions (e.g. USA version, equipped with board monitor, high cluster, etc.) is activated in the control module. Coding is used for most control modules in the vehicle except for powertrain control modules.
The various types of coding methods are
Scheme 111
- ZCS Coding.
- Coding Code (no longer supported).
- Variant Coding (DME).
- Vehicle and Key Memory Coding.
Programming is entirely different than coding. New programmable control modules contain information about the identity of the module but do not have any pre-written instructions.
During the programming operation, the appropriate specific data maps (e.g. ignition maps, fuel delivery maps, shift points, etc.) are written electronically into the EPROM of the "basic control unit". The programming data is commonly referred to as the "part number for a programmed control unit". This part number corresponds to a very specific data set.
There are two types of basic control modules: Programmable and Flash Programmable.
Programmable control modules may have instructions written to the EPROM only once. If the data set needs to be changed the EPROM must be removed from the module and replaced with a new blank one.
The EEPROMs of flash programmable control modules are soldered in and are not removable; however, they can be electronically erased and written to multiple times (14).
