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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Test Switch Terminal

The test switch terminal is located in the duty check data link connector. When the test switch terminal is grounded, the powertrain control module sets the ignition timing to the base setting.

When both the test switch terminal and the diagnostic request switch terminal are grounded simultaneously, the powertrain control module outputs the air/fuel duty cycle through the duty check terminal.