Did you try our February question?
A rear defogger grid is being tested. Technician A says that when probing a grid line, the voltmeter should decrease in its reading as the probe gets closer to the ground bus bar. Technician B says that if the voltmeter reads 12.0 volts at both ends of the grid line, there is an open in the grid line itself. Who is correct?
A. Technician A
B. Technician B
C. Bother A and B
D. Neither A nor B
You’re correct if you answered A!
Reading the same voltage at either end of the grid is the same as reading equal voltage on either side of a light bulb or any other electrical load. It indicates a fault in the ground side of the circuit so Technician B is incorrect. Technician A, however, is correct. As the voltmeter lead moves closer to the ground side of the grid line, the resistance of the grid line will increase, creating an increasing voltage drop.
But correct or not, everyone is eligible to register for the random prize drawing, sponsored by Federated Auto Parts! That's what Rick Fletcher of Rainier, Oregon, did - and he's going to receive a custom collectible diecast for his troubles!
You, too, can be a winner. Simply try our March Question of the Month and then follow the prompts to enter. Good luck!