The crankshaft sensor (DPKV, synchronization sensor, TDC sensor) is a crankshaft position sensor that is installed on vehicles with an electronic engine control system. DPKV is an element that allows the engine ECU to control the position of the crankshaft to ensure the operation of the fuel injection system. In other words, the shaft’s crankshaft position sensor (timing sensor) accurately determines when fuel needs to be supplied to the internal combustion engine cylinders.
The specified crankshaft speed sensor directly affects the operation of the engine. Any sensor malfunction will lead to instability of the internal combustion engine or a complete stop of the engine. In various designs, the crankshaft sensor is responsible for synchronizing the operation of the fuel injectors (See: What are symptoms of dirty fuel injectors?) and synchronizing the ignition. DPKV malfunctions lead to the fact that fuel is not supplied in time and ignites in the cylinders. As a result of malfunctioning fuel injection, the engine is not able to operate normally.
The function of the crankshaft sensor is that the DPKV sends signals to the ECU about the position of the crankshaft and with what frequency and direction it rotates. Different cars can be equipped with crankshaft position sensors that are different in the principle of operation, which are divided into the following types:
- Crankshaft magnetic sensor (DPKV inductive type). A feature of such sensors is that such solutions do not require a separate power supply. The formation of a signal on the ECU occurs when a special tooth (mark) for synchronization passes through the magnetic field. The specified magnetic field is created in the area of the synchronization sensor, that is, around it. In parallel with the main task of monitoring the position and rotation of the crankshaft, DPKV can also act as a speed sensor;
- Hall effect crankshaft position sensor. DPKV of the specified type is Hall sensors. In such sensors, the current begins to move when a changing magnetic field approaches the sensor. A special synchronizing disk realizes the overlap of the magnetic field; the teeth of the disk interact with the magnetic field of the DPKV. The crankshaft speed sensor of the specified type can in parallel perform the function of the ignition distributor sensor;
- Optical type crankshaft sensor. The optical crankshaft position sensor also interacts with the synchronization disc with special grooves (teeth). You can also make Holes on the disc. The specified disk blocks the optical flow that passes between the LED and the special receiver. The task of the receiver is to detect interruptions in the light flux, after which a voltage pulse is generated, which is transmitted to the engine control unit;
A common question is where the crankshaft sensor is installed. The crankshaft position sensor is enclosed in a housing similar to similar sensors in the engine management system ( camshaft position sensor, etc.). The place of its installation on the engine is a special bracket, which is located next to the drive pulley of the automobile generator. It is also possible to distinguish DPKV from other sensors by the presence of a sufficiently long wire (55-65 cm) with a special connector. Through the specified connector, the crankshaft sensor is connected to the engine control system.
This is the gap that forms between the sensor and the toothed pulley (synchronization disc). The optimal location of the crankshaft sensor is such that the gap between the core and the disc is between 0.5 and 1.5 mm. It is necessary to set the desired clearance by manipulating the gaskets (washers), which are located in the area of the seat of the crankshaft sensor and the DPKV itself.
Based on the readings of the DPKV, the ECU can determine the position of the crankshaft concerning TDC in 1, as well as in cylinder 4 of the power unit. The control unit also receives signals about the crankshaft speed and the direction in which the crankshaft performs the specified rotation. Based on the data received, the ECU generates control signals for the injection injectors, controls the ignition timing, transmits signals about the crankshaft speed to the tachometer, activates and deactivates the electric fuel pump.
Now let’s look at how to check the crankshaft sensor with your own hands in case of malfunction. To begin with, crankshaft sensor malfunctions are not common. When checking the timing sensor, you should also pay attention to the condition of the generator drive pulley. In the event of malfunctions in the operation of these elements, the engine may not start or stall after starting; the car does not pick up speed and jerks, the engine stalls on the move, etc. The dashboard usually lights up “cheсk”. Connecting the scanner to the diagnostic connector (block) will allow you to more accurately determine the breakdown by the error code, which is recorded in the ECU memory.
You can check the crankshaft sensor yourself with a multimeter tester. It is necessary to switch the device to ohmmeter mode and then measure the resistance of the crankshaft sensor winding. The resulting indicator for a serviceable DPKV should be around 800-900 ohms. In parallel with this, it is necessary to analyze the integrity of the wiring and exclude or establish the presence of mechanical damage to the sensor.
You should also add that in the case of an accurate determination of the malfunction of the crankshaft position sensor, it will be more rational to buy a new synchronization sensor without trying to repair the existing part. The retail price of DPKV for most cars remains quite acceptable, and a new high-quality crankshaft position sensor is guaranteed to ensure the correct operation of the internal combustion engine.« Back to Glossary Index