When a wiper motor shows 0 volts under operation, the most likely fault is:

• A. a short to ground on the motor.
• B. an open in the hot side of the circuit.
• C. a failed relay.
• D. a blown wiper fuse.

Answer: (B)

When a wiper motor shows 0 volts under operation, the key idea is that the motor isn’t receiving any supply voltage because the power path to it is open. The motor only runs if the hot side of the circuit delivers voltage through the fuse, wiring, and switch/relay to the motor terminals. If that feed is interrupted—an open in the hot side—the motor terminal voltage will read zero even though the switch is turned on. That’s why this symptom points to an upstream supply fault rather than a problem inside the motor windings or a short to ground. A short to ground would typically cause a surge or blow a fuse and not leave the motor reading zero volts in a normal diagnostic step, and a relay failure could also stop power, but the simplest, most common explanation for zero volts at the motor is an open on the hot side of the circuit, such as a broken wire or a failed upstream component. In practice, start by checking the hot-side supply path—fuse status, connections, and the switch/relay—to confirm voltage reaches the motor when the system is commanded.