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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Vacuum Sensor


If a MAP sensor is not used, a Vacuum Sensor may be used, although some systems may not use either component. The vacuum sensor produces low voltage (approximately 1 volt) when manifold vacuum is low, and higher voltages (approximately 4.5 volts) when vacuum is high. Normal output is 0.54 - 0.62 volts with ignition on and engine stopped.