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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Resistance Tests
















Caution Never touch terminals of ECM itself or connect voltmeter or ohmmeter. Be sure to connect ohmmeter probe from wire harness side of coupler. Be sure igntion switch is OFF. Resistance in table represents that when ambient temperature is 20°C (68°F).


1. With ignition switch Off, disconnect ECM couplers from ECM.
2. Check resistance between each pair of terminals of disconnected couplers.