Circuit/System Description

WARNING: This page is about a different car, the 2012 GMC Yukon, 2012 Chevrolet Tahoe, and 2012 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.

The crankshaft position sensor circuits consist of an engine control module (ECM) supplied 5-volt reference circuit, low reference circuit and an output signal circuit. The crank shaft position sensor is an internally magnetic biased digital output integrated circuit sensing device. The sensor detects magnetic flux changes of the teeth and slots of a 58-tooth reluctor wheel on the crankshaft. Each tooth on the reluctor wheel is spaced at 60-tooth spacing, with 2 missing teeth for the reference gap. The crankshaft position sensor produces an ON/OFF DC voltage of varying frequency, with 58 output pulses per crankshaft revolution. The frequency of the crankshaft position sensor output depends on the velocity of the crankshaft. The crankshaft position sensor sends a digital signal, which represents an image of the crankshaft reluctor wheel, to the ECM as each tooth on the wheel rotates past the crankshaft position sensor. The ECM uses each crankshaft position signal pulse to determine crankshaft speed and decodes the crankshaft reluctor wheel reference gap to identify crankshaft position. This information is then used to sequence the ignition timing and fuel injection events for the engine. The ECM also uses crankshaft position sensor output information to determine the crankshaft relative position to the camshaft, to detect cylinder misfire, and to control the camshaft position actuator if equipped.

Motor control module 1 is also connected to the crankshaft position sensor signal and low reference circuits. The motor control module uses the crankshaft position sensor output information to determine engine crankshaft position to aid in smooth engine Auto-starts. The motor control module does not need the crankshaft position sensor signal in order for the engine to start and run.