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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Voltage Signal: Description and Operation


^ Electrical load signals (component "ON") are sent to the ECU from the headlight switch, blower motor switch, cooling fan switches and rear window defroster.
^ When these loads are present, ECU activates idle speed control (ISC) valve as needed to maintain correct idle speed.