There are many strange fault phenomena, and the fault causes are different; How to find the real fault cause in the complex fault phenomenon is a “practice” for every maintenance master. This issue brings you a “strange” fault case.
1. Use A Diagnostic Expert To Read The Fault Code of ecu blindly
Use the decoder to read the fault code p01db, which is the circuit fault code, so put the troubleshooting direction on the circuit and differential pressure sensor of ecu blindly.
2. Detect differential pressure sensor harness of ecu blindly
Unplug the plug of the differential pressure sensor, measure the voltage at the female end, the voltage is 5V, 5V and 0V respectively, and measure the connection and disconnection of the three harnesses at the same time. The connection and disconnection of the harness are normal; It indicates that there is no problem with the harness. It is suspected that there is a problem with the sensor of ecu blindly.
3. Replace the POC differential pressure sensor of ecu blindly
After replacing the POC differential pressure sensor, the fault remains. There is no problem with the harness and the sensor. Now I suspect there is a problem with the software or hardware of the ECU of ecu blindly.
4. Brush ECU program with decoder
After the program is written, the fault remains. It is planned to replace the ECU in the next step. Before replacing the ECU Hardware, use the decoder to read the data stream to see if other problems can be found.
5. Use a diagnostic expert to read the data stream
No abnormality related to POC differential pressure sensor is found from the data flow.
6. Replace ECU
The fault remains after replacing the ECU.
According to the fault code p01db – the particle trap POC differential voltage signal afterrun is higher than the upper limit. Afterrun refers to the state after T15 switch is powered off. It indicates that the measuring signal line is still energized after T15 is powered off.
7. After the key is powered off, measure the voltage of POC differential pressure sensor signal line.
After the power is off, the measured voltage of the signal line is 4.9v (0V after a period of time). The fault may be the short circuit of the signal line to the power supply.
8. In order to ensure that there is no problem with the harness, re fly the POC differential pressure sensor.
After all the wires are re flown, the fault remains the same.
Through the above troubleshooting steps, the ECU, harness and sensor are excluded. At the same time, the signal line voltage can be measured after the key is powered off, so it is suspected that there is a problem with the T15 harness.
9. For T15 flying wire
The fault code is detected after the key is powered off (after run) and the speed is 0. When it is detected that the signal line voltage of POC differential pressure sensor is 0.3V to 5V and lasts for a certain time, the fault code will be reported.
The fault case is strange. There is a fault in T15 line, which does not cause the engine to shut down or make it difficult for the engine to shut down. There is no abnormality in the data flow.
This is because it takes time for T15 to jump from one state to another. When T15 is in the “off” state, due to the virtual connection of T15, the ECU is powered on briefly, but the state value of T15 will not change, resulting in no change in the state of the engine and maintained at afterrun. However, at this time, the ECU will have voltage output, which leads to, The POC voltage is detected to be too high, and then a fault is reported. The reporting of this fault is closely related to the manufacturer’s time calibration.
There are many places where we need ultrasonic for after-sales maintenance, such as cleaning oil nozzles, oil pumps, etc. with the help of ultrasonic high-frequency vibration, we can remove pollutants that are difficult to clean by other methods and corners that are difficult to touch. Similarly, we can apply this technology to cleaning POC, and the effect is very good, but the operation cost and difficulty are high.