3.1.3 - LDR DIS Ignition Control Module (ICM) The DIS ICM incorporates a thick film ceramic substrate assembly and three output drivers mounted on a metal base plate and potted in a plastic housing. It performs the following functions: 1) Provides ground for the ignition system through two of the mounting screws - without proper ground, the ICM and PCM will not operate and the engine will not start. 2) Selects which coil to fire - the ICM uses the CMP signal to select the proper coil to fire. At crank, the ICM looks for CMP transitions and prepares to synchronize it to coil 2 firing events. 3) Controls current to the coil primary circuits - the SPOUT signal generated by the PCM controls the coil on and coil off times. SPOUT, therefore, controls both ignition timing and dwell. 4) Limits current flow to the coils to 5.5 +/- 0.5 amps 5) Generates the Ignition Diagnostic Monitor (IDM) signal to the PCM. Every coil firing generates a flyback voltage which is conditions by the ICM and output to the PCM. 6) Provides some Failure Modes and Effects Management (FMEM) - fires the coils in the absence of SPOUT.
3.1.4 - LDR DIS Powertrain Control Module (PCM) The PCM performs the following ignition-related functions: 1) Uses the CKP signal to calculate engine rpm and determine crankshaft position. 2) Uses the CMP signal to synchronize fuel injectors to the proper cylinder and for proper injection timing. 3) Determines ignition timing and coil dwell time. The SPOUT signal provides this information to the ICM. 4) Monitors IDM to determine if coil primary circuits are intact.
3.1.5 - LDR DIS Ignition Coil The DIS Coil assembly contains three coils for a 6-cylinder engine. Each individual coil has two high voltage towers which each go to an individual sparkplug, wired in series.
3.1.6 - LDR DIS Failure Mode and Effects Management (FMEM) If the CMP sensor fails, the ICM will randomly select one of the two coils to fire. If hard starting results, turning the key off and then cranking again will result in another "guess". Several attempts may be required until the proper coil is selected, allowing the vehicle to be started and driven until repairs can be made. If the SPOUT line fails, the ICM will fire the coils directly from the CKP sensor. This results in fixed 10 deg BTDC timing and fixed dwell.