There are many electronic components in cars. One of the key sensors is the camshaft sensor. If there is a problem with this small part, it will affect the operation of the entire car. This article will explain this component in detail. By reading this article, you can know how to test the quality of the camshaft sensor. Learn camshaft sensor testing techniques.
Test camshaft sensor
What is a camshaft sensor?
The camshaft position sensor is a sensing device, also called a synchronization signal sensor. It is a cylinder identification and positioning device that inputs the camshaft position signal to the ECU, which is the main control signal for ignition control.
Camshaft sensor detail view
Camshaft sensor function
Camshaft Position Sensor (CPS), its function is to collect the camshaft angle signal and input it into the electronic control unit (ECU) to determine the ignition time and fuel injection time. Camshaft Position Sensor (CPS) is also called Cylinder Identification Sensor (CIS). In order to distinguish it from crankshaft position sensor (EPS), camshaft position sensor is generally represented by CIS. The function of the camshaft position sensor is to collect the position signal of the valve camshaft and input it into the ECU so that the ECU can identify the cylinder compression top dead center to perform sequential injection control, ignition timing control and knock control. In addition, the camshaft position signal is used to identify the first ignition moment when starting the engine. Because the camshaft position sensor can identify which cylinder piston is about to reach top dead center, it is called a cylinder identification sensor.
Types of camshaft position sensors
1. Magnetoelectric induction type
The magnetoelectric induction speed sensor and crankshaft position sensor are installed in the distributor at upper and lower levels. The sensor consists of a permanent magnet induction detection coil and a rotor (timing rotor and speed rotor), which rotates with the distributor shaft. The timing rotor has one, two or four teeth, and the speed rotor has 24 teeth. The permanent magnet induction detection coil is fixed on the distributor body. If the speed sensor signal and crankshaft position sensor signal are known, as well as the working sequence of each cylinder, the crankshaft position of each cylinder can be known. The rotor signal discs of magneto-inductive speed sensors and crankshaft position sensors can also be mounted on the crankshaft or camshaft.
2. Hall effect formula
The Hall effect speed sensor and crankshaft position sensor are signal generators that utilize the Hall effect. The Hall signal generator is installed in the distributor, coaxial with the distributor head, and is integrally fixed on the distributor plate by a packaged Hall chip and a permanent magnet. The number of notches on the trigger impeller is the same as the number of engine cylinders. When the blades on the trigger impeller enter between the permanent magnet and the Hall element, the magnetic field of the Hall trigger is bypassed by the blades. At this time, no Hall voltage is generated and the sensor has no output signal; when the notch on the trigger impeller enters the permanent magnet When between the sensor and the Hall element, the magnetic lines of force enter the Hall element, the Hall voltage increases, and the sensor outputs a voltage signal.
3. Photoelectric type
The photoelectric crankshaft position sensor is generally installed in the distributor and consists of a signal generator and a signal plate with a light hole. The signal plate rotates together with the distributor shaft. There are 360 photolithographic slits in the outer ring of the signal plate, which generates a signal of 1° crankshaft angle. Slightly inside, there are 6 light holes evenly spaced at 60° intervals, generating a signal of 120° crankshaft angle. Signal, one of the light holes is wider to generate a signal relative to the top dead center of cylinder 1. The signal generator is installed on the distributor housing and consists of two light-emitting diodes, two photosensitive diodes and a circuit. The light-emitting diode is facing the photodiode. The signal disk is located between the light-emitting diode and the photosensitive diode. Since there are light holes on the signal disk, light transmission and light shielding alternately change. When the light beam of the light-emitting diode shines on the photosensitive diode, the photosensitive diode generates a voltage; when the light beam of the light-emitting diode is blocked, the voltage of the photosensitive diode is 0. After these voltage signals are shaped and amplified by the circuit part, the signals at crankshaft angles of 1° and 120° are sent to the electronic control unit. The electronic control unit calculates the engine speed and crankshaft position based on these signals.
Camshaft sensor fault symptoms and troubleshooting
After the camshaft sensor fails, the main symptoms of the car will be difficulty in starting, inability to accelerate, increased fuel consumption, abnormal body shaking, vehicle lighting failure, sudden flameout when the car is hot, etc. For the above reasons, you need to go to a repair shop to repair the specific fault and Repair camshaft sensor.
Camshaft sensor fault symptoms and troubleshooting
The following is a detailed introduction:
1. Difficulties in starting the vehicle:
When a camshaft sensor fails, its ignition sequence will malfunction, making it difficult to start the vehicle.
2. Unable to accelerate:
After the camshaft sensor fails, the ECU cannot detect the position change of the camshaft, causing the engine's intake system and exhaust system to fail to work properly, ultimately causing the car's weak acceleration.
3. Increased fuel consumption:
When the camshaft sensor fails, the computer fuel system will malfunction, and the injector will also inject faulty fuel, thereby increasing the vehicle's fuel consumption.
4. Abnormal body shaking:
Abnormal body shaking is also one of the symptoms of camshaft sensor failure.
5. The vehicle fault light is on:
If the vehicle check light comes on, the signal sensor may be faulty.
Camshaft position sensor detection tips
The camshaft position sensor is installed on the oil supply pump camshaft or on the camshaft drive gear. Its function is to collect the position signal of the valve camshaft and input it into the ECU so that the ECU can identify the compression top dead center of the 1st cylinder, so as to control the sequential injection amount, injection time and knocking control.
In addition, the camshaft position signal is also used to identify the first ignition moment when the engine is started. Because the camshaft position sensor can identify which cylinder piston is about to reach top dead center, it is called a cylinder identification sensor.
When the camshaft position fails, the engine is difficult to start or cannot be started, and the fault light comes on. Therefore, if you learn to detect the camshaft position sensor, you will find the cause of the fault faster and solve the fault problem.
1. Appearance inspection
The detection steps are as follows:
Step 1: Turn off the ignition switch.
Step 2: Unplug the sensor harness connection terminal.
Step 3: Visually inspect the connector housing for damage.
Step 4: Visually inspect the stylus for dust, debris, or moisture.
Step 5: Visually inspect the contact pins to see if they are bent, broken, indented, or sticking out.
Step 6: Remove the sensor and check whether there are iron filings adsorbed on the permanent magnet part.
2.Air gap inspection
The detection steps are as follows:
Step 1: Turn off the ignition switch.
Step 2: Unplug the sensor harness connection terminal.
Step 3: Use a feeler gauge to check the air gap, measure different positions of the signal wheel, and find the maximum and minimum values.
Standard value: The standard gap between the sensor and the signal wheel is generally 0.8~1.5mm, and the difference between the maximum and minimum air gap should not be too large.
3. Detect sensor resistance value
The detection steps are as follows:
Step 1: Turn off the ignition switch.
Step 2: Unplug the sensor.
Step 3: Use a multimeter to check the resistance value between terminals 1 and 2 on the wiring harness side.
Standard value: 650~1000Ω.
4. Check the wiring harness continuity
The detection steps are as follows:
Step 1: Turn off the ignition switch.
Step 2: Unplug the sensor.
Step 3: Use the resistance setting of the multimeter to measure the resistance values between terminals No. 1 and 30, terminals 2 and 23, and terminals 3 and 30 to determine whether there is a short circuit or open circuit in the external line. Fault.
Standard value: resistance value <10Ω.
5.Detect signal voltage
The detection steps are as follows:
Step 1: Turn off the ignition switch.
Step 2: Unplug the oil pressure sensor plug.
Step 3: Turn the ignition switch ON and try to start the engine.
Step 4: Use a multimeter to check the voltage value between sensor side terminals 1 and 2.
Standard value: There should be voltage pulse signal output.
6.Related fault codes
1. Fault code 753 or 778.
Cause: The ECM cannot detect the camshaft position sensor signal.
Result: The fault light is yellow and the engine starting performance is poor.
2. Fault code 731: The engine speed signal is inconsistent.
Reason: The crankshaft speed and camshaft speed signals are inconsistent.
Result: The fault light is yellow, the engine works roughly and the starting performance deteriorates.
Nantian Electronics a professional distributor of electronic components, providing a wide range of electronic products, saving you a lot of time, effort and cost through our meticulous order preparation and fast delivery service.
Share this post
