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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Powertrain Control Module & Body Control Module

POWERTRAIN CONTROL MODULE

The PCM communicates with the BCM over the Class 2 serial data circuit. When the BCM enters tamper mode, it sends a Class 2 message to the PCM in order to disable the fuel injection system. If the BCM receives the expected ignition code, the BCM sends a class 2 message to the PCM in order to enable the fuel injection system. The PCM then allows the vehicle to start.