It's always interesting to see how others have approached similar problems. During a rare free moment I disassembled the original Nissan front wiper delay module. Here are the guts:


It's a nice design but probably more complex than it needs to be. It looks like it will last as long as the rest of the truck if the relay holds up. Here is what some of the stuff is:

IC1 is the brains, a Microchip PIC16FR711. No doubt chosen for it's A/D converter but has way more pins than are needed here.

IC2 is a reset minotor for the micro. This is redundant, the PIC has most of this built-in.

IC3 is a voltage regulator

The blue thing is a 4 MHz ceramic resonator, the master clock.

The box with "3059 BC" on it is the relay that ultimately drives the motor.

Q1 is the transistor that allows the PIC to drive the relay coil.