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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Ignition Coil: Testing and Inspection

Ignition Coil Resistance Check:






PRIMARY RESISTANCE CHECK

Check primary resistance across coil terminals as indicated on image. If not within specification, replace coil.

SECONDARY RESISTANCE CHECK

Check secondary resistance as indicated on image. If not within specification, replace coil.

COIL CASE RESISTANCE CHECK

Check insulation resistance between primary terminal and coil case. It should be 10M ohms or more. Replace coil if it does not test as specified.