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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Vehicle Speed Signal

42LE - Automatic Transmission
VEHICLE SPEED SIGNAL
The vehicle speed signal is calculated from the Output Speed Sensor. The PCM converts the OSS signal into a roughly 8000 pulse per mile vehicle speed signal (using pinion factor information programmed into its memory), and sends it to the PCM.

The PCM, in turn, sends the vehicle speed message across the PCI bus to the Instrument Cluster to display vehicle speed to the driver.