The ignition system used on the 4.2L, 4.6L, 5.4L and 6.8L engine is an electronic distributorless ignition system known as the High Data Rate ignition system. These engines utilize what is known as an integrated ignition system in which the Powertrain Control Module (PCM) performs all the control functions and the Ignition control Module (ICM) is eliminated.
The integrated ignition system consists of the PCM, Crankshaft Position (CKP) sensor, CKP trigger wheel, and a coil pack(s) on the 4.2L and 4.6L engines and individual coils known as "coil over plug" on the 5.4L and 6.8L engines. The system operates as follows: The CKP sensor produces a signal generated from the induced voltage created as the trigger wheel on the crankshaft or flywheel passes the sensor. This signal is received at the PCM as a Profile Ignition Pickup (PIP) signal. The PCM processes the PIP signal along with signals received from other sensors on engine speed, engine temperature, and engine load, and determines the correct ignition timing and grounds the proper ignition coils in the coil pack or the individual coils. When the ignition coil is grounded, an Ignition Diagnostic Monitor (IDM) signal is sent to the PCM. This signal provides the PCM with diagnostic information and confirms that the coil fired and is also used to operate the vehicle's tachometer (if equipped).