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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Switch Monitor Test

The Switch Monitor Test checks input signals sent from the Electronic Control Module (ECM).

The Switch Monitor Test is a unique and separate test from the Key On Engine Running (KOER) self test. This test is performed by actuating a series of switches and verifying their operation and input signals.

All switches must be "Off" at the beginning of the test and only one switch at a time must be actuated during the test.