Two types of knock sensors are installed on VAZ vehicles: one-contact and two-contact. When diagnosing this sensor, refer to the precautions when repairing this system.
It is necessary
- - multimeter (tester);
- - socket wrench
Instructions
Step 1
Please note: on VAZ cars, access to the knock sensor is hampered by the intake module. As a consequence, remove the knock sensor by touch. To facilitate the process, remove the engine mudguard and dismantle the sensor by getting close to it from the bottom of the machine (on the inspection pit or overpass).
Step 2
To remove the knock sensor, unscrew the sensor fixing bolt from the cylinder block with a socket wrench. Remove the transducer from the locating pin and slide it out from under the inlet module. Disconnect the harness connector from the sensor by pressing the latch.
Step 3
To check the sensor, connect a multimeter to its terminals, which is included in the voltmeter mode with a measurement limit of up to 200 mV. To correctly connect a single-contact sensor to the device, connect the negative wire (black) of the device to the sensor ground (the place where the mounting bolt is installed). Connect the positive wire (red) to the signal wire located in the sensor connector. Two-contact sensors are connected with both leads to the tester wires observing polarity.
Step 4
Then use a screwdriver to lightly tap the sensor body to simulate detonation. In this case, the tester should show voltage surges of 40-200 mV, depending on the strength of the shock. In case of any malfunction of the sensor, there will be no reaction to shocks. The sensor should be replaced. Remember that in some cases the devices are not able to detect a weak signal and the volmeter will indicate a sensor malfunction.
Step 5
Switch the tester to resistance measurement mode and connect it to the sensor leads. In this case, it is desirable that the device be able to measure infinitely large resistances. A working knock sensor on VAZ cars should have a very high resistance tending to infinity.
Step 6
More accurate checks of the knock sensor are possible only at a special stand. Install the tested sensor in reverse order. Tighten the fastening bolt with a torque of 20-25 Nm.
