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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Vehicle Speed Sensor: Description and Operation

VSS:





The reed type Vehicle Speed Sensor is built into the back of the speedometer. The speed sensor converts the speedometer gear revolutions (vehicle speed) into pulse signals, which are then sent to the Control Unit to be used as a reference signal. This signal and others are calculated in determining ignition timing and idle speed control.