This sensor is used by the logic module to determine the position of the crankshaft and the engine speed. It sends a pulse each time the crankshaft has reached it's "base timing" ignition point (normally 12 degrees advanced from TDC). This information is used to determine when to fire the ignition coil and also, in conjunction with the fuel injector sync pickup sensor, when to fire the fuel injectors. The ignition reference sensor uses a hall effect sensor that is located beneath the distributer cap which senses the presence of a permanent magnet on the other side of a rotating "shutter" that is attached to the rotor. The sensor has an open collector output that is pulled up to 5V by the logic module. Each time the hall effect sensor detects the magnet (when the crankshaft is at the base timing point), the output is pulled down to 0V. The shutter has 4 openings, so there is one "low" pulse for each rotation of the crankshaft, and 4 pulses for each rotation of the distributer rotor and camshaft (for 2.2L and 2.5L).
If the logic module hasn't received a signal from the sensor since the last time the module's memory was cleared, a fault code 11 is automatically stored and the engine will not start. As soon as a pulse is received from the sensor (by cranking the engine), the code is cleared and the engine will start. If the signal is lost while the engine is running, the engine will stall and no fault code will be stored. The logic module's memory must be cleared and the engine cranked to set the code and determine of the sensor has failed.
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Copyright © 1996-2003 Russ W. Knize.