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

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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 the 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 DK GRN wire (CKT 389), which feeds the Instrument Panel Cluster. The PCM also produces an output at the DK GRN/WHT wire (CKT 817) which feeds the Speed Sensitive Suspension Module (4.9L Powertrain) or Road Sensing Suspension (RSS) Module (Northstar Powertrain).