Fault 1
Chery QQ6 a car, using SQR473 mounted engine electronic control system combined matching QR513 type manual transmission, the user reflects a car accident occurred previously, but the risk of vehicle repair warning light has been unable to work.
After receiving the car, the test found that the car left and right turn signals can work properly, but the hazard warning lights did not work. According to the symptom of the car, the author of the preliminary analysis of possible causes of the above-described malfunction includes: hazard switch 30, the power supply line F7 (15 A) fuse burning, damage and hazard lamp switch BCM internal fault. Given the car left and right turn signals are working properly, and therefore will not consider other fault lines.
I first examined the hazard switch fuse F7, found in good condition, which is measured using a multimeter is completely normal. Then, I try to change the hazard switch, but test failure remains. Then I tried to change the BCM, but the fault is still not improve. But after careful observation I found that every time you open the car hazard warning hazard warning light will flash once the switch, then there will be no response until after the close switch is turned on again, it will flash once. According to the test results, you can determine the BCM, switches and fuses are normal, then what reason did not think of it? Will there be anything to do with the last service work? So I again had to communicate with the user. The user does not provide other clues.
FIG 1
FIG. 2
At this time, I decided to query the last car file maintenance, may be able to be found. Search for car maintenance records after the last incident, that the car had been replaced two headlamps (Figure 1), is it the replacement of these two headlamp is faulty? Try holding the mentality, I disconnected the two headlight harness connector, turn on the hazard warning lights switch again, this time hazard warning lights actually back to normal. Further examination, I found that the replacement of the vehicle headlamp assembly 2 by the turn signal lamp bulb 4 (FIG. 2), with the vehicle turn signal and the original group 1 is an LED lamp (FIG. 3), the maintenance personnel is obviously for the wrong headlights.
Figure 3
Note here that the vehicle headlamp assembly can not be seen from the appearance of the LED mounting steering lamp or turn signal lamp form, in order to avoid wrong change , preferably turns on the headlights when replacing the back cover, which is observed in the form of good installation of turn signal. So why the car after replacing the lamp in the form of headlamps turn signal, hazard warning lights when opening the flash only once it? This is because the car BCM intelligent overload protection. When the BCM detects the load current exceeds the collector with the rated range, it will cut off the power of the electrical appliances, to prevent overload and burned lines and BCM. In order to determine whether the correct determination of the author, the author of the measured current hazard warning lights in the actual work. When the vehicle headlamp using the LED mounted in the form of the flasher, the current work hazard warning lights of about 2 A; car when in use with a headlamp bulb in the form of turn signal, hazard warning work the current is approximately 8 A. Therefore, after changing the lamp in the form of a headlamp flasher, each open hazard switch, hazard warning lights flash only once, then it was cut off the power BCM.
After replacement with two matching car headlamp assembly, failure to completely eliminate.
Summary: The car will be the same as the reason for the wrong element of fault is relevant service personnel only looking at the headlights look, and what form of turn signal from the outside can not see, they He did not go to check carefully the part number. By the maintenance of the car, we should note that, even for the same type of vehicle, if configured differently, then there may be parts not universal. Therefore, when the replacement auto parts, it is best to check part numbers of parts, because parts of the part number is ldquo; identity rdquo ;, the only way to ensure that does not change the wrong parts. Of course, for insurance purposes, it is best to do some corresponding checks.
Fault 2
a Chery A516 sedan, equipped with engines using SQR481F joint electronic control system, matching QR519 type manual transmission, vehicle miles traveled 13,000 km, the car users reflect the cold morning after the engine is started within about 40 min step on the accelerator pedal of the vehicle no response.
Since the user has to drive the vehicle to heat car, vehicle fault no diseaseshape. I first consulted the relevant user car failure. Say users, the car emerged after the failure in cold weather, and as the weather cools, the fault duration also will be longer. Based on our experience in the maintenance, due to colder weather in the north, the engine in the winter is just starting in about 10 min with a load if hard acceleration, the engine will accelerate slow and pant phenomenon. However, the user indicates the vehicle can accelerate from about 40 min after the start, there are some problems. The author then connected to the vehicle fault diagnostic apparatus for detecting an engine control system, but did not find any fault code, the vehicle engine is running hot and completely normal. According to the actual situation of the car, I recommend that you leave the car until the next morning to conduct field test.
Figure 4
The description of the symptom user, I believe that possible causes include relevant lines in the presence of cold car phenomenon of virtual access, resulting in signal transmission error; accelerator position sensor poor working state when cold; electronic throttle body has issuing phenomenon when cold; faulty brake switch; unstable engine control unit. To the first two days in the morning, before starting the vehicle, first connect the fuel pressure gauge and fault diagnostic. Dynamic data flow found by reading the engine control system, an engine coolant temperature of -7 deg.] C, inlet temperature of -6 deg.] C, an accelerator position sensor 1 voltage is 0.37 V, accelerator pedal position sensor 2 is 0.72 V, the electronic throttle voltage (FIG. 4) a throttle position sensor 1 is 4.28 V, a throttle position sensor voltage electronic throttle 2 is 0.68 V, were within the normal range. The system fuel pressure at the engine start to 380 kPa, it is also completely normal. A successful start of the engine, after starting the engine idle speed is 1 100 r / min, the engine operation is stable. When the vehicle warm-up for about 5 min, when the accelerator pedal is depressed the engine speed with no lift, the data stream read found, accelerator pedal position sensor voltage in the accelerator pedal in the end does not change. This situation is definitely not normal, if the engine control unit as a result of warm-up prohibition control strategy or some engine speed increase, it should be able to see the signal change of the accelerator pedal position sensor. Now accelerator pedal position sensor signal does not change, indicating a major fault in the accelerationA pedal position sensor, due to the accelerator pedal position sensor and the position of the minimum voltage value is normal, so that the possibility of failure of the line can be excluded.
Figure 5
After removing the accelerator pedal position sensor assembly, the author found that the accelerator pedal position sensor there are a lot of mucus flowing, feels like a rubber-like substance. Test for an accelerator pedal assembly (FIG. 5), the smooth acceleration of the engine test, using a fault diagnostic observation data flow engine control system, the display device accelerator pedal position sensor signal voltage can correspondingly vary with the position of the accelerator pedal. Replace the old accelerator pedal assembly, still can not accelerate. Thus, the presence of an internal fault can be determined accelerator pedal assembly.
After replacing the accelerator pedal assembly, troubleshooting.
Summary: accelerator pedal position sensor car non-contact Hall sensor, the probability of the actual use of the sensor is small damage. However, this cold car accelerator pedal position sensor insensitive reactions may be related to rubber-like material on the sensor. The substance adhered to the surface of Hall sensors may not sense the signal at the lead temperature is too low.
Fault 3
2006 annual tiggo a 1.6 L, to reflect the user right rear car power window down switch can not control the rise drop control window.
Figure 6
After receiving the car, the test was found, the user reflect the true fault. Then I try to control left front and right rear window master switch, the normal window lift described gate unit and the motor is no problem, but also that the signal can reach the master switch right rear windows switch. According to the current situation, the author doubts right rear power window switch (FIG. 6) is damaged or right rear window regulator down signal to the gating circuit unit disconnection place.
Figure 7
According to this idea, I first remove the right rear power window control switch, is connected directly across the line with rising and falling control signal terminal terminal found that the window can not lift, power windows DescriptionThe control switch has not failed. Total disconnect connector right rear door, from which the down signal to the control unit, the window can be smoothly decreased, indicating a failure in the connector to the right rear right rear door power window switch this circuit (FIG. 7). Using a meter to measure the line paragraph, really it is infinite. Remove the harness segment careful examination revealed right rear power window down signal lines yellow / white line is disconnected the internal wire (insulation but intact).
After the wire harness is connected, test troubleshooting.
Summary: The fault analysis is simple easily place, the key note of the correctness of jumper terminals should operate. Further, at the line circuit of the internal wire harness, it is easily overlooked when troubleshooting. Therefore, we must be careful in the exclusion of similar failures.
(Qin Zhigang)