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)

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Controller Area Network Data Link






CAN Data Link

The Engine Control Module (ECM) communicates with all databus capable control modules by a CAN Data Link.

The databus capable control modules (i.e. Engine Coolant temperature Sensor) are connected by two data bus wires which are twisted together (CAN_High and CAN_Low), and exchange information (messages) to the Engine Control Module (ECM). Missing information on the databus is then recognized and stored as a malfunction.

The Engine Control Module (ECM) illuminates the Malfunction Indicator Lamp (MIL) through the CAN data link and tells the Malfunction Indicator Lamp (MIL) to turn on, turn off, or blink.