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)

Or, hide this message: temporarily or permanently

Ignition Module Operation

IDIS Ignition Coil And Module Assembly:






This IDI module monitors the crank sensor signals and based on these signals sends a reference signal to the ECM so that correct spark and fuel injector control can be maintained during all driving conditions. During cranking, the IDI module monitors the "sync pulse" to begin the ignition firing sequence and below 700 rpm the module controls spark advance by triggering each of the two coils at a pre-determined interval based on engine speed only. Above 700 rpm the ECM controls the spark timing (EST) and compensates for all driving conditions. The IDI module must receive a "sync pulse" and then a crank signal in that order to enable the engine to start. The IDI module is not repairable. When a IDI module is defective, the module is replaced as a separate component.