Operation CHARM: Car repair manuals for everyone.
Manuals through 2025 now available!

Our trusted friends have launched a new website named LEMON, which has newer manuals. It also contains all the CHARM manuals.

LEMON is the spiritual successor to CHARM, I recommend you try it!

Link: lemon-manuals.la or lemon-manuals.org.ua

(Some people have issue connecting. LEMON is investigating. For now, use Firefox or change your DNS server)

Or, hide this message: temporarily or permanently

PCM EPROM

The PCM has an Erasable Programmable Read-Only Memory (EPROM) computer chip that contains the calibration information used by the PCM to control fueling, idle speed, ignition timing, transaxle shifts, and vehicle emissions. The calibration information is based on various aspects of the vehicle, such as engine size, vehicle weight, transaxle type, final drive ratio, etc. The EPROM is programmed (flashed) with the calibration information that is critical to the proper operation of the PCM. The EPROM is soldered into the PCM and cannot be serviced separately. Replacement PCMs used for service require programming after installation.