The headlight washer pump motor powers the washer pump in order to clean dirt from the headlight lens. The headlight washer pump motor is connected to the power supply in the vehicle and drives the rotary pump in order to push water out of one or more nozzles attached to the washer and a wiper cleans off the lens. These are occasionally prone to blockage so should be checked regularly.
The motor which drives the headlight washer pump is often the same motor which drives the windscreen washers. This means that any issue with the headlight washer pump motor could also impact on the windscreen washers. They are usually activated with the same stalk lever and the headlight washer usually operates on every 4-5 movements of the windscreen wiper arms.
Failure of the headlight washer pump motor can be potentially dangerous for two reasons. Firstly, the windscreen washers and headlight washers will not work correctly impacting on visibility. Secondly, in the case of xenon headlights it’s a legal requirement to have working headlight washers as the dirt on the headlights can refract the light around the road causing issues for other drivers.