Where Is the Data Stored In A Control Module?

Where is the Data Stored in a Control Module?
One of the differences between a personal computer and a vehicle control module is where the data is stored. The computer uses a hard drive, while a vehicle control module uses either an EPROM or an EEPROM depending on the system.

EPROM (Electrically Programmable Read Only Memory)




An EPROM is a removable chip with multiple connector pins which plug into the printed circuit of the control module.

When re-programming this type of control module, the EPROM must be removed and a new "blank" EPROM installed prior to programming

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 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:
- Characteristic maps for;
Ignition, Injection, Purge control, etc...
- Characteristic curves
- Control constants