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Home >> Ford >> 1991 >> Mustang L4-140 2.3L SOHC >> Repair and Diagnosis >> Powertrain Management >> Relays and Modules - Powertrain Management >> Relays and Modules - Computers and Control Systems >> Engine Control Module >> Description and Operation >> Ignition Diagnostic Monitor (IDM) Operation
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Ignition Diagnostic Monitor (IDM) Operation

The Ignition Diagnostic Monitor (IDM) is a function of the Distributorless Ignition System (DIS) module. The DIS module sends information on system failures to the Electronic Control Assembly (ECA), which stores the information for diagnostic self test. The IDM signal also is used to drive the vehicle instrument tachometer and the test tachometer for system diagnosis.
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