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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Voltage Signal: Description and Operation


The electrical system voltage changes due to various conditions, in turn affecting the amount of fuel delivered. The ECU compensates for this by constantly monitoring the system voltage and generating a correction factor to ensure the pulse sent to the injectors is correct, regardless of system voltage.