2. Disconnect the vacuum hoses from the drive.
3. Connect a hand vacuum pump to the drive (front axle deactivation circuit), as it shown on the picture.
4. Create a vacuum of 26.6 kPa and check that the rod moves to the left,
5. Disconnect the hand vacuum pump.
6. Connect a hand vacuum pump to the drive (front axle connection circuit), as it shown on the picture.
7. Create a vacuum of 26.6 kPa and make sure that the rod moves to the right.
If the drive does not operate as described, replace the drive.