How to Test the Crankshaft Sensor on an Cutlass Ciera


The crankshaft sensors in your Cutlass Ciera provide signals to the on-board computer indicating the engine's crankshaft position in it's rotation and which cylinder is on the compression stroke. The engine in the Ciera uses two crankshaft position sensors: a low-speed sensor, called 24X, and a starting/high speed sensor, called 7X. If a sensor fails, the engine will not start, or it will have rough idle and and low-speed engine misfire. Testing the crankshaft sensor is done with a digital volt/ohm meter. These tools are available at most large auto parts stores.

Things You'll Need

  • Digital volt/ohm meter
  • Apply the parking brake and lift the passenger-side front wheel of the Ciera off the ground using a floor jack positioned under the front sub-frame. Remove the passenger-side front wheel. Remove the splash shield in the inner fender well by using a pair of pliers to remove the two plastic rivets and a wrench to remove the 10 mm bolts. Lay the splash shield aside.

  • Test the 24X sensor at the crankshaft for resistance by unplugging the wiring harness electrical connector from the sensor located to the right of and behind the crankshaft pulley. Set the digital volt/ohm meter to "Ohms." Touch the probe ends of the meter leads to the terminals inside the sensor's electrical connector. If the resistance is 0 ohms (internally shorted) or "Infinite" (internally open) ohms, replace the sensor.

  • Test the wiring for short to ground by touching the negative (black) meter lead to the engine block while touching the positive (red) meter lead to a terminal in the wiring harness connector. Repair the wiring harness if the resistance is 0 ohms on either of the terminals in the harness connector.

  • Test the 7X sensor, located on the firewall side of the engine near the center of the engine block, for resistance. Unplug the sensor's electrical connector and touch the meter leads to the two terminals in the sensor. Replace the sensor if a resistance of either 0 or "Infinite" ohms is measured.

  • Test the wiring for a short to ground by touching the negative meter lead to ground while touching the positive meter lead to the wiring harness terminals. Replace the wiring harness if 0 ohms resistance is measured on either terminal .

Tips & Warnings

  • A common problem for the V-6 engine in the Oldsmobile Cutlass Ciera is faulty wiring that runs from the ignition module to the 7X sensor.
  • Wear safety glasses and work gloves when working around a running engine to prevent serious injuries.
  • Do not use an analog meter for this repair. An analog meter causes high-current flow and may damage the on-board computer.


  • "Advanced Engine Diagnostics"; Jendam Inc.; 2001
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