It's the kearns relay, aka intermittent wiper. That's when the relay comes into play. Behind the main fuse box, triple wide relay, white box. Shake it, probably something gone loose. If you're good at soldering, it can be fixed. If the break in an unsolder-able area, buy a new one. It controls your turn signal, etc. so other encased relays are not far behind it.

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"Patty" - 1994 E320 Touring "Sportline" 172/174 124.092
"Lucy" - 2006 Toyota Land Cruiser