Chevrolet released its first self-manufactured compact pickup, the S10, in 1982. Between 1982 and 1987, the largest engine available on the S10 was the 2.8-liter V-6. In 1988, Chevrolet stuffed the new 4.3-liter Vortec engine into the compact pickup. With each rotation of the crankshaft in the 2000 S10’s 4.3-liter, the crankshaft position signal relays four electrical pulses to the vehicle control module. The VCM then adjusts fuel and spark as needed to match the speed of the crankshaft. Finding the crankshaft sensor is a little tricky if you don’t know where to look. If you need to replace the crankshaft position sensor, you must perform a relearn procedure, which requires a diagnostic scanner.
Raise the front of the S10 with a floor jack and slide jack stands under the frame. Lower the vehicle to the jack stands.
Crawl under the front of the S10. If the vehicle has an under-engine skidpan, remove the bolts and washers securing the skid pan, using a ratchet and socket, and remove the skid pan.
Look behind and to the passenger’s side of the crankshaft pulley, and find the crankshaft position sensor.
Follow steps 1 through 3 in the section titled “Finding the Crankshaft Position Sensor.”
Pry upward on the locking tab on the crankshaft position sensor’s wiring harness, using a flathead screwdriver, and unplug the wiring harness.
Remove the bolt securing the crankshaft position sensor to the engine block, using a ratchet and socket. Pull the sensor from the engine.
Apply a thin coat of new engine oil to the O-ring on the new crankshaft position sensor, using your fingers. Guide the new sensor into its hole in the engine until it fully seats on the engine and hand-tighten the sensor’s retaining bolt.
Tighten the crankshaft sensor bolt to 15 foot-pounds with a torque wrench and socket. Plug the wiring harness into the receptacle on the sensor.
Slide the washer’s onto the skid pan’s bolts, if needed. Raise the skid pan into place, if applicable, and hand-thread its retaining bolts. Tighten the skid pan bolts to 24 foot-pounds with a torque wrench and socket.
Raise the truck off the jack stands with a floor jack and remove the jack stands. Lower the vehicle to the ground.
Proceed to the section titled “Crankshaft Position Sensor Relearn Process.”
Look under the driver’s side of the dashboard and find the data link connector, the male plug in the same shape as the connector on the OBD-II scanner. Plug the OBD-II’s connector into the DLC.
Block the front and rear wheels with wheel chocks.
Start the engine and place the transmission in “Neutral.” Allow the engine to idle until it reaches operating temperature, roughly halfway up the temperature gauge. Turn off all of the engine accessories, including air conditioner, radio, headlights and turn signals.
Turn on the scanner, if it did not automatically turn on when you started the engine. Initiate the OBD-II scanner’s “Crankshaft Position System Variation Learn Procedure.” This process varies greatly, depending on the style of scanner you use, so refer to on-screen prompts and the scanner’s instructions for specifics.
Press and hold the brake pedal to start the relearn process.
Raise the engine speed to 4,000 rpm slowly and hold it. Once the engine speed starts decreasing automatically, release the accelerator pedal.
Turn the ignition to the “Off” position once the scanner prompts you that it has completed the relearn procedure.
