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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Circuit Operation

The Vehicle Speed Sensor is a gear-driven Permanent Magnet Generator housed in the vehicle's transaxle. This sensor generates a sine wave output with a frequency proportional to vehicle speed. The PCM converts this signal to an output that is switched to ground at a frequency of 4000 pulses per mile at the (817 CKT) wire output. This output is pulled up to 0.6 volts or greater by the components that use this speed signal as an input.