Fault phenomenon
    A public open Di multi-purpose car, rain when the EPC light is always bright.
    Troubleshooting and troubleshooting
    According to the owner described, driving to the way suddenly felt the accelerator pedal failure. At this point regardless of the throttle step on the small step, the speed is the same, but also a red rushed. Flat road 4 block speed is 40 ~ 50km / h, neutral when the engine speed is higher. [Note: Dashboard EPC (electronic power control) light is lit, the engine into the fail safe mode, the accelerator pedal does not work, can be low speed to the repair shop, also known as "limping home function." ]
    Maintenance personnel with a decoder to read the code, read the fault code is 18038 / incidental, meaning the accelerator pedal position sensor signal is too weak / sporadic fault. With the decoder to eliminate the code, EPC lights are extinguished, after the test all normal. The owner took the car away. A few months later, the same failure occurred again, maintenance personnel and staged a few months ago the scene, the vehicle and all normal, the owner will take the car away. The vehicle had a few days, the same failure occurred again. Maintenance personnel first eliminate the fault code, and then check the accelerator pedal position sensor to the engine control unit between the lines, did not find the circuit has a circuit or short circuit. The test did not fail 30km, maintenance personnel think that this test has been that the accelerator pedal position sensor and line no problem, do not need to repair. Three days later, the same fault appeared again. However, the owner provides an important clue: the failure of all rainy days. Maintenance personnel that is due to heavy rain on the rainy day, causing the accelerator pedal position sensor or its line break or short circuit failure. After using the decoder to eliminate the fault code, immediately go to the test. Because it was just in the rain, and sure enough to drive less than 10km in the rain, the failure occurred again: EPC lights lit, the vehicle can not run, or fault code 18038 / incidental. And the elimination of the fault code, and then test did not fail. A few days later, the fault has emerged, or rain off the fault, sunny without trouble. Maintenance personnel have been helpless, and help maintenance personnel.
    Maintenance personnel to carefully analyze the phenomenon of failure and repair process, that the phenomenon of rain and rainy weather. In order to confirm this idea, and then did not rain, with car wash guns, so that the engine is running, but after half an hour, the failure did not appear. After the flame, covered with airtight car cover, and put a day, the engine compartment and passenger cabin full of moisture, but after the launch again, the failure did not appear. The experiment negates the hypothesis that the rainy tide causes a malfunction.
    Re-analysis of the phenomenon: as long as the rain driving, occasional failure occurs frequently. According to experience, frequent occasional failures are often associated with lines. Rainy day is the use of the wiper, so in front of the open wiper (turn on the front window grinder) to run the engine, but no failure, and driving a scraper test, 7 ~ 8km after the failure appears The.
    Check the engine control unit and the wiper harness carefully by dismantling the front neck guide plate and the sink board. As a result, it was found that the engine control unit harness and the wiper arm were close together, and the wiper was suspected to be working with the engine Unit harness phase scratch. When the wire harness is viewed, it is found that the harness has a small wear port, where one of the wires is ground and the wire is the signal line of the accelerator pedal position sensor G67 to the engine control unit. Found the cause of the failure, the harness was processed, the technical director felt the wire harness and wiper working arm too close, the car running wire harness and wiper arm may also scratch. So do not solve this too close to the problem, the fault is still not completely ruled out. At this time to participate in the inspection of the electrical technician put the engine control unit anti-face fixed, so that the harness from the wiper far. So the engine control unit for a fixed face, so that the harness away from the wiper. And then driving a wiper test 20km, the fault did not appear.