Highlander Headlight Washer Issue

That's strange! Some cars use the same pump for both. Check the washer pump fuse, it might control both. Listen when you try to activate the washer – can you hear the pump motor running? If not, it's likely electrical. If you hear it, a clog is more likely.

Good call on the fuse! I'll check that in the morning. If the fuse is okay and I don't hear the pump, what's next? Electrical issues sound like a pain...

If the fuse is fine and no pump sound, the pump motor or a bad connection is most likely. Wiring corrodes, especially near the pump. Locate the pump, usually in the washer fluid reservoir, and check the wiring connector for corrosion. If you're comfortable with a multimeter, check if the pump is getting power when activated. If not, a mechanic is safest. Could be a bad relay, but that's harder to diagnose without tools.

Took it to my local mechanic. Turns out it was a bad cable connection to the pump. Cost me 165€ to sort it. Thanks for the help!