A case of large fault caused by small parts is extended to analyze the detection of crankshaft position sensor of vehicle stalls.
Fault vehicle information: a national Sanjiang huaishuoling supporting 4DA1 engine and edc16c39 Bosch computer board of vehicle stalls.
Fault phenomenon: during driving, the gearbox makes a sudden abnormal noise, the vehicle stalls, and then does not stop. As soon as you take a taxi, the fault light comes on.
Relevant fault codes:
The transmission makes a strange noise and the vehicle stalls. It was originally caused by it
Fault analysis: combined with the phenomenon of vehicle not landing, fault code and driver description. The most likely cause of the analysis is a component failure of the crankshaft position sensor.
Troubleshooting steps:
1. Remove the crankshaft position sensor for inspection.
2. The crankshaft position sensor is damaged. After replacement, you can drive to the repair shop to check the abnormal noise.
3. Disassemble the gearbox and check the inside of the ladle.
4. If the bearing ball is found, it is a guide bearing by visual inspection of vehicle stalls.
5. If the flywheel signal tooth is damaged, clean the ball and replace the parts. So far, the fault has been completely eliminated of vehicle stalls.
This fault belongs to the circuit fault associated with mechanical failure. In the maintenance, more communication with the owner is needed, combined with the fault phenomenon. It is very helpful for us to quickly and thoroughly solve the fault problem of vehicle stalls.
The crankshaft position sensor is damaged, which can be observed intuitively. However, when we encounter a fault in the sensor circuit, we need to use tools to measure. Now let’s have a detailed understanding of the circuit detection of the lower crankshaft position sensor based on this fault case of vehicle stalls.
1、 Harness inspection procedure
Open circuit check:
1. Turn off the ignition switch.
2. Unplug ECU engine harness a plug.
3. Unplug the harness connector of bending position sensor.
4. Measure the resistance between the harness of bending position sensor and ECU harness. Normal value: ~ 0 Ω / pin 1 to ECU pin a27~ 0 Ω / pin 2 to ECU pin A12. If the resistance is abnormal, check whether the harness is open and the connector is damaged.
Short circuit check:
1. Turn off the ignition switch.
2. Unplug ECU engine harness a plug.
3. Unplug the harness connector of bending position sensor.
4. Measure the resistance between the harness of bending position sensor and ECU harness. Normal value: ≥ 1m Ω / pin 1 to body grounding~ ≥ 1m Ω / pin 2 to body grounding. If the resistance is abnormal, check whether the harness is short circuited to the ground and the connector is damaged.
2、 Component inspection
Resistance check:
1. Turn off the ignition switch.
2. Unplug ECU engine harness a plug.
3. Unplug the harness connector of bending position sensor.
4. Measure the resistance between pin 1 and pin 2 of curve position sensor harness. Normal value: 770-950 Ω (at 20 ℃)
If the resistance is abnormal, the crankshaft position sensor is damaged.
Crankshaft sensor signal voltage detection:
1. Turn off the ignition switch.
2. Unplug ECU engine harness a plug.
3. Unplug the harness connector of bending position sensor.
4. Use jumper box and oscilloscope to measure the signal voltage of crankshaft sensor.
Note: the positive pole of the oscilloscope is connected to ECU pin a27 and the negative pole is connected to A12.
If the waveform is abnormal: the curve position sensor is installed incorrectly; Flywheel disc error; The bending position sensor is damaged.
1. Turn off the ignition switch of vehicle stalls
2. Rotate the wheel disc so that the engine is at the top dead center of cylinder 1 of vehicle stalls
3. Check the crankshaft signal panel, sensor installation clearance: 1mm, and the number of teeth is shown in the figure below. If the result is abnormal: the clearance is too large, the deflection sensor / flywheel disc is installed incorrectly, the flywheel disc does not match, and the deflection sensor is damaged of vehicle stalls
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