In a ground-side switched rear wiper circuit, a voltage reading at the ground-side connector shows full source voltage. What is the most likely interpretation?

• A. The rear wiper switch is off.
• B. The ground is open.
• C. The rear wiper is not turned on.
• D. The motor is seized.

Answer: (C)

In a ground-side switched circuit, the motor’s return path to ground is controlled by the switch. When the switch is on, the ground path is completed and the ground-side terminal is at or near ground potential, allowing current to flow and the motor to run. If you measure that ground-side connector and you see the full battery voltage, it means there is no solid ground connection at that point — the ground path is not closed. The motor’s other end is tied to supply, so with the switch open the ground-side node can float up to the source voltage, indicating the switch is not turned on. This is the most likely interpretation: the rear wiper is not turned on. The idea that the ground is open is related but less specific here; the key clue is that the switch controlling the return path isn’t closed, so the circuit isn’t completed and the wiper isn’t running.