Slide 61 of 123
Notes:
This 22,000 ohm resistor is connected to the negative terminal of the coil primary in the Ignition Diagnostic Monitor (IDM) circuit connected to the PCM. Every time the PCM sends a SPOUT signal to the module to fire the coil, the PCM expects to see a voltage signal on the IDM line telling it the coil actually fired.
If there’s no confirmation signal on the IDM circuit after the SPPOUT signal
is sent, the computer assumes that a misfire has occurred, and stores a trouble
code.
Don’t confuse the IDM with the operation of the OBD II Misfire Monitor.
