What is the purpose of capacitors in some intermittent wiper systems?

• A. To provide intermittent wipe timing
• B. To power the motor directly
• C. To permanently increase motor speed
• D. To protect the circuit from voltage spikes

Answer: (A)

Intermittent wipe timing is controlled by a timing circuit that uses a capacitor. In these setups, the capacitor and a resistor form an RC network that controls how long the system waits between wipes. When the intermittent setting is chosen, the capacitor charges through the resistor and, once it reaches a threshold, the control circuit triggers the wiper motor. After the wipe, the capacitor discharges and creates the delay before the next wipe cycle. The length of that delay is determined by the RC time constant, so changing the capacitor value (or the resistor) changes how long the interval lasts. This timing function is the reason the capacitor is used here; it’s not meant to power the motor directly or permanently increase its speed.