Land cruiser 4000, can't get on the four-wheel drive, 4LO flashes, and the engine fault light is always on. How to solve it?

The Land Cruiser 4000 can't be hung on the four-wheel drive, with 4LO flashing and the engine fault light on all the time. The reasons are as follows:

First of all, the transfer box is responsible for the connection of the drive mode. Internal gear failure or controller failure will cause the four-wheel drive mode to be fooled. You can determine the fault point by disconnecting the power supply of the transfer box controller, and then troubleshoot it.

Second, the wheel controller is faulty. All four wheels have solenoid valve controller devices. If something goes wrong, the four-wheel drive will not be connected. If the power of the single-wheel controller is disconnected, the fault point can be found and then the fault can be eliminated.

Third, there is too little gearbox oil. The control computer will limit the use of the four-wheel drive mode, thus reducing the damage of vehicle parts. It can be solved by replacing the gearbox oil. The specific operation steps are as follows:

1. Drain transmission oil.

2. Remove the bottom shell screw.

3. Remove the bottom shell.

4. Install a new bottom shell.

5. refueling is complete.