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This system does not use the ignition module used on the DI systems in the past. The VCM controller now controls the ignition control (IC) and bypass functions.
The crankshaft sensor, located in the front engine cover, is perpendicular to a target wheel attached to the crankshaft. The target wheel is equipped with slots situated 60 degrees apart. As the crankshaft rotates, the target wheel rotates past the crankshaft position sensor. The rising and falling edges created by the slots cause a signal to be sent back to the VCM. This signal occurs three times per crankshaft revolution and is referred to as the 3x signal for V6 applications. The signal occurs four times per crankshaft revolution and is referred to as the 4x signal for V8 applications.
The VCM then utilizes this 3x (V6) or 4x (V8) signal in order to provide the correct spark to the engine by way of the single coil driver module. The single coil driver module is basically an electronic switch that when commanded by the VCM, causes the primary coil voltage to breakdown, energizing the secondary coil and providing a spark via the coil wire to the distributor cap. The distributor consists of the following components:
• Cap and rotor
• Camshaft position sensor
• Gear drive and shaft
The camshaft drives the distributor shaft which rotates providing a spark to the correct cylinder by way of the cap and rotor. The camshaft position (CMP) sensor functions much like the crankshaft sensor previously described but provides only a 1x signal to the VCM. That is, for every 2 rotations of the crankshaft, there is 1 rotation of the camshaft. Note that the camshaft position sensor will not affect driveability.
The sole purpose of the camshaft position sensor is to provide the VCM with the necessary information for the misfire diagnostic trouble codes (DTCs).
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