The Volkswagen T4 Transporter 1995 van features a resistive-based fuel sender to measure the fuel level in the vehicle's fuel tank. Here's an explanation of how it typically works:
1. Float Mechanism: The fuel sender consists of a float that moves up and down based on the fuel level in the tank. As the fuel level decreases, the float descends, and as the fuel level increases, the float rises.
2. Variable Resistor: Attached to the float is a variable resistor (also called a potentiometer). As the float moves, it rotates the wiper contact of the variable resistor, changing its resistance value. This change in resistance corresponds to the varying fuel levels.
3. Fuel Level Circuit: The variable resistor forms part of a voltage divider circuit. One end of the variable resistor is connected to a constant voltage source, while the other end is grounded. The wiper contact of the variable resistor is connected to a wire that goes to the fuel gauge in the instrument cluster.
4. Fuel Gauge Reading: The fuel gauge is essentially an ammeter that measures the current flowing through it. As the resistance value of the variable resistor changes due to the float position, the amount of current flowing through the fuel gauge also changes. This variation in current moves the needle of the fuel gauge, indicating the corresponding fuel level.
5. Ground Connection: The fuel sender unit also includes a ground connection to ensure proper circuit completion and accurate readings.
When the fuel level is full, the float will be at its highest position, causing the variable resistor to have a low resistance value. This, in turn, allows more current to flow through the fuel gauge, resulting in a higher reading on the fuel gauge. As the fuel level decreases, the float moves down, increasing the resistance value of the variable resistor. Consequently, less current flows through the fuel gauge, causing the needle to move towards the "empty" mark.
It's important to note that the fuel sender unit may have slightly different configurations depending on the specific variations of the Volkswagen T4 Transporter 1995 van. However, the basic principle of using a variable resistor to measure fuel level remains the same.
