Crankshaft Position Sensor

Operation

The crankshaft position sensor detects the crank angle (piston position) of each cylinder, converts it to a pulse signal and inputs it to the engine control module. The engine control module computes the engine speed and the intake air amount for one stroke and outputs the injector drive signal and injection command signal based on this signal.

Power to the crankshaft position sensor is supplied from the ignition switch (IG), and the ground is located in the engine control module. A 5V Voltage is applied from the engine control module to the crankshaft position sensor output terminal, and the crankshaft position sensor generates a pulse signal as it switches from OPEN to SHORT (power transistor inside the sensor switches ON/OFF) between the output terminal and the ground.

Troubleshooting Hints

Hint 1 If unexpected shocks are felt during driving or the engine stalls suddenly during idling, shake the crankshaft position sensor harness. If this causes the engine to stall, poor contact of the sensor connector is suspected.

Hint 2: If the crankshaft position sensor outputs a pulse signal when the ignition switch is turned to ON, (without starting the engine), the crankshaft position sensor or engine control module is probably defective.

Hint 3: If the tachometer reads 0 rpm when the engine that has failed to start is cranked, faulty crankshaft position sensor or broken timing belt is suspected.

Hint 4: If the tachometer reads 0 rpm when the engine that has failed to start is cranked, the primary current of the ignition coil is not turned on and off. Therefore, troubles in the ignition circuit and ignition coil or faulty ignition power transistor is suspected.

Hint 5: If the engine can be run at idle even though the crankshaft position sensor reading is out of specification, troubles are often in other than the crankshaft position sensor.

Examples

(1) Faulty water temperature sensor
(2) Faulty idle air control motor
(3) Poorly adjusted basic idle speed






Inspection





Using Oscilloscope





Harness Inspection