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 logical successor to CHARM, I recommend you try it!

Link: lemon-manuals.la

Serial Data Communications

Regulations require that all automobile manufacturers establish a common communications system. The communication between the powertrain control module and the off-board diagnostic equipment (scan tool) is achieved on a serial communication line. Serial data is sent in linear form, one bit at a time, over the communication line.