Ignition Diagnostic Monitor

The Ignition Diagnostic Monitor (IDM) is:

• A function of the ignition control module (ICM) (12K072) .
• The ignition control module sends information on system failures to the powertrain control module (PCM) (12A650) , which stores the information for diagnostic self tests.
• The IDM signal is also used to drive the vehicle instrument tachometer and/or test tachometer for diagnosis.