Here's a general guide on how to switch between fuel tanks in a 2001 Freightliner truck with dual fuel tanks:
1. Locate the fuel tank switch on the truck's dashboard or console. It may be labeled "Fuel Tank Selector," "Tank Switch," or something similar.
2. Make sure the truck is in neutral and the parking brake is engaged.
3. Press or toggle the fuel tank switch to the desired position. The switch may have options like "Tank 1," "Tank 2," or "Both."
4. Allow a few seconds for the fuel system to adjust.
5. Start the engine and check the fuel gauge to ensure that the selected fuel tank is being used.
6. If necessary, repeat steps 2-5 to switch between fuel tanks again.
Please note that the specific location and operation of the fuel tank switch may vary depending on the exact model and year of your Freightliner truck. It's recommended to consult your truck's owner's manual or refer to a qualified mechanic if you need assistance with switching fuel tanks.