Intermittent wiper systems can vary the time between wipes using which components?

• A. A capacitor only
• B. Both a resistor and a capacitor
• C. A resistor only
• D. Neither component

Answer: (B)

The delay between wipes is produced by an RC timing network in the wiper control. A capacitor stores charge while a resistor controls how quickly that charge builds up. The control circuit monitors the capacitor voltage and fires the wipe when a threshold is reached, then the cycle repeats. The interval is set by the time constant tau = R × C, so changing either the resistance or the capacitance changes how long the delay lasts. Because the delay relies on both storing energy (capacitor) and regulating the charge rate (resistor), both components are used.