Toyota Corolla can not start the fault phenomenon: Toyota Corolla car equipped with 3s-fe engine, the car in the past driving the occasional turn off the phenomenon, but can be activated immediately after the flame, but this time no reason after the engine is turned off.
    Toyota Corolla can not start troubleshooting: after the car check results are as follows: 1. engine start without high pressure fire; 2. engine fuel injection nozzle can not measure the fuel injection pulse; 3. Open the ignition switch, engine failure warning light does not shine (Normally open the ignition switch, the engine fault light should be lit. After the engine starts the electronic control unit on the electronic control components for 4 ~ 6s self-test, to confirm the fault when the fault light is always bright, no fault when the fault light goes out). Taking into account the car ignition and fuel are ecu direct control, it is likely that ecu lack of working voltage and can not work due.
    First check ecuefi insurance, insurance without burning phenomenon. With a dedicated engine fault detector for testing, detector display no communication links. With a short connection to connect the diagnostic plug te1 feet and e1 feet, to manually read the fault code, the fault light is still not bright. In order to prevent e1 feet off bad, direct te1 feet ground, fault lights did not respond. The owner reflects the fault light before the repair is good. This is more sure that the engine does not catch the fire is due to ecu caused by the work.
    Find the car circuit diagram, as shown in line to line ecu all the power lines batt, + b, + b1 and all the cable line e, e01, e02, found normal. We had to ecu shell removed, its internal components for testing. Measured by the input line of fire, take the wire can be sent to ecu internal, pin no problem, and its internal components did not significantly burn, open welding phenomenon. In order to further determine the quality of the computer, we made a replacement ecu assembly comparison test. The replacement of a normal driving the same model car ecu after the start of the test, still can not catch the fire. And the car ecu installed on the normal car, the engine will be able to start the fire once, and the engine fault detector with ecu smooth contact, the engine conditions are normal, indicating that the car computer is intact, then the reason out Where?
    To this end, had to press the circuit diagram of the lines carefully "inventory." When the throttle valve operating voltage is detected, suddenly light up. Working voltage is not even 5v, only less than 0.7v voltage. From this part of the circuit shows that the intake pressure sensor, throttle opening sensor and co-concentration regulator of the three variable power sharing of a power cord, the power sent by ecu regulator, the normal value should be 5v. Replace ecu contrast experiment has been determined ecu is normal, then it should be able to send 5v normal voltage. Must be on the line somewhere there is a short circuit caused by the voltage drop on the line is too large. Unplug the ecu plug, unplug the throttle position sensor plug, measure the throttle position sensor harness side line 4 (working power) to ground resistance, found less than 1ω, abnormal value. Unplug the intake pressure sensor plug, measure the harness side line 3 (working power) to ground resistance, found that only 1ω. Check the co-concentration regulator variable resistor, pull out the variable resistor plug, wire harness side line 3 to ground resistance, found with the harness shaking its resistance sometimes infinite, sometimes 0. This shows that there may be a co-concentration regulator variable resistance of the wiring harness out of the problem.
  The inspection revealed that the harness was passed from below the bottom of the fender and was pierced by a small hole in the fender located at the right headlamp and connected to the variable resistor located there. Remove the wing liner to pull out the wire harness and check that the wire has been squeezed out at a distance from the plug, and that the copper wire has been peeled off from the outer insulation. Bandaged wire harness and re-fixed wire harness, co concentration regulator variable resistance, start the engine, start the fire, troubleshooting.
    According to the owner to reflect, six months ago the car had an accident, and replaced the bumper, the right side of the fender and the right lights. It is necessary to replace the bumper and the fender when the harness did not notice the harness damage. At the same time the damaged wiring harness did not immediately cause failure, with the future driving vibration and wave, wiring harness fixed point loose. Coupled with the cold and cold deformation of the wiring harness, making the harness break directly contact with the fender, resulting in 5v voltage directly with the car body short circuit. When the short-circuit current is too large so ecu can not work.
    This short circuit on the line is different from our usual common within a short circuit of electrical components. It can be seen from the circuit diagram, the water temperature sensor, intake air temperature sensor, throttle position sensor and other components of the power line and ground line are provided by the computer to form a closed circuit. On the one hand to rely on reliable; the other hand, the components and ecu constitute a circuit can be monitored. Once the electrical components within the short circuit, due to the protection of ecu circuit regulation, it will not make the current consumption is too large. At the same time ecu enabled backup program, you can slowly go home will not be halfway to anchor. But when the external components of the circuit and the body of the car, ecu can not control the current, it caused ecu work disorders, and even ecu bridge circuit imbalance and not work, also led to the engine without the phenomenon of the car.
    A small line of short circuit failure even spent more than 3 days time, and finally found to be the previous maintenance left the "tail". Vehicle maintenance is the maintenance efficiency and maintenance of the organic unity of quality, not only for maintenance efficiency, while ignoring the quality of maintenance. In the maintenance process to pay attention to prevent the tide, not because it is only a small negligence, a small fault on the area, or in the future will lead to a big mistake. The old saying is good, "not because of good and small, not because of evil and small." Thousands of miles of embankment in the nest, the philosophy of which fascinated deep.