In our Jeep Compass 2018 1.4 4x4 vehicle, there was a 4x4 malfunction at first, a humming sound was heard, then we found the front and rear differential of the vehicle from another vehicle and replaced it. Now there is no fault light on, but the vehicle does not switch to 4x4 and you hear a loud sound when you switch from automatic mode to manual mode when the vehicle exceeds 40 kmh and makes a sharp maneuver or enters a pothole or enters the vehicle. "Lok" sound. What do you think is the reason?