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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IAC Duty Cycle

Scan Tool Range 20% to 40%. The IAC Duty Cycle parameter indicates the opening of the idle air (bypass) passage of the IAC motor in a measurement of a percentage. The AC Duty Cycle percentage will increase when the PCM commands a larger idle air passage opening. The IAC Duty Cycle percentage will decrease when the IAC motor responds to a PCM command for a smaller idle air passage opening.