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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Engine Cooling Fan Control

The Engine Cooling Fan control is partitioned between the Powertrain Control Module (PCM) and the Body Function Controller (BFC) via Class 2. The main algorithm control resides in the Body Function Controller (BFC). The Body Function Controller (BFC) sends a fan speed command to the Powertrain Control Module (PCM). The Powertrain Control Module (PCM) processes this command along with its own fan request and determines what the actual fan speed should be.