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
If it fails: lemon-manuals.org.ua

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Tachometer

The CKP sensor is used as an input for tachometer information. The CKP sensor sends the ECM an A/C voltage signal. The ECM uses the A/C voltage signal to calculate RPM. The ECM sends an averaged tachometer message to the BCM via the CAN bus where the BCM sends a message to the I/P cluster over the Class II link. The ECM averages the tachometer information to ensure smooth tachometer fluctuations.