Fault Symptom:The customer reported that the vehicle could not be charged at home with an AC charger. When the charging cable is plugged into the vehicle, the charging indicator lights up red, the charger shows that it is connected, and at the same time, the meter shows that the left charging port is damaged, and the **display shows that it cannot be charged, as shown in Figure 1 Figure 4.
Troubleshooting:First look at the fault code, there is a P33E800 charging slot AC charging plug lock in the OBC, the fault of mechanical failure, as shown in Figure 5.
According to the fault phenomenon and fault code, the possible fault causes are: high-voltage charging slot failure, charging locking motor circuit failure, high-voltage charger failure, and charging gun locking motor failure.
First of all, according to the external charger displaying "Connected", you can judge that the OBC to the external charger CC cable is normal.
Querying the technical information, there are cases of similar fault phenomena, such as "the charging plug is slightly tilted downward, which causes the charging plug to not lock and thus cannot be charged" (as shown in Figure 6). According to the information, see that the plugged charging port is normal.
Next, the drive test is carried out on the left charging gun lock lock (as shown in Figure 7): the locking motor can be extended and retracted normally, and the charging gun lock lock is normal.
After plugging in the charging cable, check the actual value and find that the lock value of the charging plug is "unlocked" (as shown in Figure 8), indicating that it is abnormal. Under normal circumstances, after the OBC and the external connection are established, it will be locked immediately, and then the CP will communicate, indicating that the problem is here.
The motor voltage and motor position signal were tested with an oscilloscope, and it was found that when the AC charging cable was inserted, the voltage output was seen three times, and the position signal of the locked motor was also shown to have a waveform output (as shown in Figure 9). After that, the charging indicator flashes red.
Why does the motor drive 3 times in a row, with questions about the working waveform of the normal vehicle locking motor, when the locking motor is turned on, the position signal is a signal voltage of 9V (as shown in Figure 10).
From the above measurements, we can determine that there is a problem with the position sensor of the locked motor (as shown in Figure 11). Since the sensor and motor are assemblies, troubleshooting after replacing the locking motor.
Fault Summary:The problem in this case was caused by a malfunction of the position sensor that locked the motor. Because the position of the locking motor detected by the OBC is incorrect, it triggers its continuous action, and when the required position is not reached after 3 times, the system will report the mechanical lock failure.
For the case of AC charging failure, we need to know the charging process: first (OBC) the on-board charger detects the CC and CP signals of the AC charging interface (charging gun insertion, guide signal), and after confirming that the connection is correct, the gateway is notified through the communication network to wake up the BMS high-voltage battery control unit, and the BMS sends instructions to the on-board charger to charge, and at the same time closes the main relay, and the high-voltage battery battery starts charging.
In case of related faults, the signal timing can be analyzed through waveform display, which can quickly confirm the direction of the fault and improve the ability to solve maintenance faults.