Circuit inspection and routine troubleshooting of pure electric vehicles

1. Line inspection
2. Harness connector inspection
   ①Check whether the electrical plug-in and the wiring harness plug-in are plugged together, and check whether they are plugged in place.
   ② Check whether the wiring harness and the pins are firmly connected, and whether the pins in the plug-in have any abnormal phenomena such as withdrawal or bending.
   ③ Check whether the position of the plug-in wiring harness is correct according to the pin definition in the wiring harness diagram.
3. Power supply check
   ①Use a special meter to check whether the power supply is normal, and pay special attention to whether the power supply value is within the normal working range of the electrical equipment.
   ②Check whether the fuse corresponding to the electrical equipment is blown, if it is blown, replace it.
   ③ Check whether the wire protective layer is damaged or leaked.
4. Ground check
   ① Check whether the grounding of the wiring harness of the electrical equipment is firm with the grounding of the body.
   ② Check whether the grounding point of the wiring harness is in good contact with the body.
   ③ Use a multimeter to check whether the ground wire harness is well connected to the body.
5. Power consumption check
   Some electrical equipment not only has a power supply, but also has an energy-consuming power supply (ACC power, IG power, etc.). When inspecting this type of electrical equipment, focus on the following.
   ① Confirm that the power consumption corresponds to the gear.
   ② Check whether the plug-in of the electrical equipment and the plug-in of the wiring harness are inserted correctly, and check whether they are inserted in place.
   ③ Check whether the wiring harness and the pins are firmly connected, and whether the pins in the plug-in have any abnormal phenomena such as withdrawal or bending.
   ④ Check whether the position of the plug-in wiring harness is correct according to the pin definition in the wiring harness diagram.
   ⑤ Use a multimeter to test the continuity of the relevant lines.
6. Check the controller signal line
   ①Understand the control strategy and failure mode, and preliminarily determine the fault point.
   ②Check whether the terminal plug-in has wrong needles, back needles, backward needles, etc.
   ③ Use a multimeter to check the continuity of both ends to see if it is short-circuited with the body, and whether it is short-circuited with other circuits in the plug-in.
7. CAN bus inspection
   ①Check whether the terminal plug-in CAN-H and CAN-L have wrong needles, retracted needles, backward needles, etc.
   ②In the case that the negative pole of the battery is not connected, use a multimeter to check the resistance of any CAN line with a CAN plug-in. If it is not the standard value (usually 60Ω), unplug the CAN plug-ins one by one until the 60Ω resistance value appears, then unplug There is a problem with the plug-in or powered device.
   ③Use PCAN to read the CAN bus data, identify the error frame, and power off the controller to observe the change of the error frame. When the error frame disappears, it is basically determined that there is a problem with the module.
8. General troubleshooting
9. The performance of the vehicle in need of maintenance
   ① Abnormal motor starting noise.
   ②The temperature of the coolant continues to be too high, the coolant does not flow, and there is leakage.
   ③The motor has stuck phenomenon and abnormal noise.
   ④ There is excessive vibration when the motor is running.
   ⑤ The motor cannot be started.
   ⑥ There is oil leakage in the motor assembly.
   ⑦The motor assembly has peculiar smell discharged.
   ⑧ The power is significantly reduced.
   ⑨ The lower part of the vehicle is leaking (not the air conditioner drainage).
   ⑩ Air leakage of the tire: When turning, there is excessive tire noise; tire wear is uneven.
   ⑪ When driving in a straight line on flat ground, the vehicle deviates.
   ⑫ Abnormal noise related to the movement of the suspension device.
   ⑬ The braking function is lost; stepping on the brake pedal feels soft; when stepping on the brake pedal, the pedal almost touches the floor; the braking deviation is obvious.
   ⑭The test temperature of the motor coolant continues to be high.
   ⑮Battery capacity decreased significantly.
   ⑯ The battery temperature continues to be high, the overheat protection starts, and there is no power output.
   If the above situation occurs, you should contact an authorized service shop to repair the vehicle as soon as possible.
10. The smart entry and smart start systems are not working properly
    (1) Possible reasons
    ①There are strong electromagnetic wave emitting devices nearby, such as TV towers, power stations, broadcasting stations, etc.
    ② Carry the smart key together with a communication device, such as a two-way radio communication device or a mobile phone
    ③ The smart key is in contact with or covered by metal objects.
    ④Operate the micro switch too fast
    ⑤ The smart key is too close to the door handle.
    ⑥ Others operate the wireless remote control function on another car nearby.
    ⑦The battery is exhausted.
    ⑧The smart key is near high-voltage equipment or equipment that produces noise.
    ⑨ The smart key is carried together with the keys of other vehicles’ smart entry and start systems or other devices that emit radio waves.
    ⑩The smart key is placed in some special places, such as on the dashboard, in the glove box, on the floor, etc.

(2) Treatment measures
①Using the mechanical key attached to the electronic smart key to unlock/lock.
②Using the wireless remote control function to unlock/lock all doors.
③The battery is exhausted, it is recommended to contact an authorized car service shop to replace the battery.
④ If the smart entry and smart start system cannot operate normally due to malfunction, it is recommended to contact an authorized car service shop.

3. General charging failure
   The general charging fault causes and solutions are shown in Table 1.
4. Airbag maintenance
   In the following cases, it is recommended to contact a BYD authorized service station for repair immediately.
   ①The airbag has been inflated and deployed.
   ② Failed to deploy the airbag in the event of an accident at the front of the vehicle.
   ③ The airbag cover has been scratched, cracked or otherwise damaged.
   ④The airbag warning light on the combination meter is abnormally lit. Note: When the power supply gear of the whole vehicle is in the “OK” gear, the airbag warning light will be on for about 5s and then turn off, indicating that the system is normal. If the airbags are switched off, the warning light will stay on, but the protective function is no longer available.
   a. The power supply gear of the vehicle is in the “OK” gear. After 5s, the warning light does not turn off or turns off and then turns on again.
   b. The vehicle power block is in the “OFF” block, and the warning light is on.
   c. When the car is running, the warning light is on or flashing.
   d. When the front passenger seat airbag switch points to “ON”, the front seat airbag warning light will illuminate.
   e. When the front seat airbag switch points to “OFF”, the front seat airbag warning light goes out.
5. EPB manual release function fails
   Press and hold the EPB switch for more than 2s to release the EPB function. After release, go to an authorized service shop to check the brake pedal switch signal and related parts and lines in time. If the EPB function still cannot be released, contact an authorized service shop for repair immediately.
6. Tire pressure monitoring system fault alarm display and measures
   The tire pressure monitoring system fault alarm display and measures are shown in Table 2.
7. The radar system cannot detect obstacles or the detection distance is inaccurate
   ①There is dirt, water or mist on the sensor.
   ② There is snow on the sensor or it is frozen.
   ③The sensor is covered by other objects.
   ④ The vehicle rolls obviously or is overloaded too much.
   ⑤ On particularly bumpy roads, slopes, gravel roads and grass
   ⑥ The sensor is repainted.
   ⑦ Noise interference from vehicle speakers and other vehicles.
   ⑧ There is another vehicle with a parking assist system nearby.
   ⑨ Install a traction ring on the vehicle.
   ⑩ The bumper or sensor has received a strong impact.
   ⑪ The vehicle is approaching a high or tortuous curb.
   ⑫ In extremely hot or cold weather.
   ⑬ A non-original inferior suspension is installed.
   ⑭The material and shape of the obstacle itself make radar detection difficult. For example, the obstacles are wires, fences, ropes, cotton, snow and other materials that absorb radio waves, objects with sharp edges and corners, low obstacles, obstacles with the upper part extending outward to the direction of the vehicle, objects on the bumper, excessive Objects near the vehicle, people near the vehicle (depending on the type of clothing).
8. There are no obstacles around the vehicle, but the buzzer sounds
   The main reason for this phenomenon may be that the external power wave interferes with the sensor. If the buzzer keeps beeping, the system may be faulty and you should contact an authorized service shop for overhaul.
9. VDC not working
   In addition to the possible failure of the system itself, the failure of the VDC may be caused by the following reasons.
   ① Drive on a very steep road.
   ② Driving on unstable roads, such as turntables, ferries, elevators, etc.
   ③Use non-original designated wheels or tires.
   ④Use the non-original designated drive motor control system related components or the components are seriously aging.
   ⑤ Use non-original brake system-related components or components that are seriously aged.
   ⑥Use of non-original specified suspension system components or components are seriously aging
10. Multimedia system failure
    Multimedia system failure information, causes and countermeasures are shown in Table 3.