Saturn Coupes/Sedans/Wagons 1991-1998 Repair Guide

Crankshaft Position Sensor (CPS)

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OPERATION



The crankshaft position sensor is mounted in the engine block, below the intake manifold. It is a simple pulse generator that signals the DIS module when specific crankshaft position markers move past it. The crankshaft position sensor defines the engine position. A crank pulse occurs at each occurrence of Top Dead Center (TDC), at 60 degrees After Top Dead Center (ATDC), and at 120 degrees ATDC. A seventh pulse, referred to as the sync pulse, occurs at 70 degrees ATDC at the No. 1 cylinder.

TESTING



If there is no rpm signal or no ignition output, unplug the sensor and connect an ohmmeter across the terminals. Resistance should be 700-900 ohms. The sensor and its circuit have a polarity, meaning if the sensor wiring is reversed, the PCM sees an open circuit. Reversing the CPS wires will result in a no-start condition.

For more information regarding the crankshaft position sensor and the ignition system, refer to Engine Electrical of this guide.

REMOVAL & INSTALLATION



  1. Disconnect the negative battery cable.
  2.  
  3. Raise and support the vehicle safely.
  4.  
  5. Detach the electrical connector from the sensor, located at the lower rear of the engine block.
  6.  
  7. Unfasten the sensor retaining bolt, then remove the sensor from the engine.
  8.  

To install:
  1. Lubricate the sensor O-ring with clean engine oil and install the sensor into the engine block.
  2.  
  3. Install the sensor retaining bolt and tighten to 80 inch lbs. (9 Nm).
  4.  
  5. Attach the CPS electrical connection.
  6.  
  7. Lower the vehicle and connect the negative battery cable.
  8.  

 
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