Two technicians are discussing a fuel gauge on a General Motors vehicle. Technician A says that if the ground wire's connection to the fuel tank sending unit becomes rusty or corroded, the fuel gauge will read lower than normal. Technician B says that if the power lead to the fuel tank sending unit is disconnected from the tank unit and grounded (ignition on), the fuel gauge should go to empty. Which technician is correct?

a. Technician A only

b. Technician B only

c. Both Technicians A and B

d. Neither Technician A nor B

b. Technician B only

Explanation:

There is a float connected to the variable resistor in a fuel tank unit. The resistance of the variable resistor also changes as the fuel level changes. The tank unit's resistance changes, the dash mount gauge also changes and available on driver's display.

If the tank transmitter is disconnected, the operation will not take place and the resistance change will not be transmitted to the dash unit. The needle will therefore remain the empty one at all times. Even after being rusty, the ground wire connection to the fuel tank will be able to conduct. Hence Technician B is correct and Technician A is incorrect.