It means there's something wrong with the car circuit. In this case, it should be to find a professional maintenance of the car circuit master to repair. Remember not to modify the circuit without permission, otherwise the consequences are very serious, it will burn part of the car or the whole circuit. Therefore, in case the rear charger does not have a power supply, it is better to let professionals use special tools to repair it.
It's a wiring problem. We can check it.