This circuit automatically rolls up a car’s electric windows when it rains. The windows are rolled up one at a time while the system monitors the window motor current. When the motor stalls, the system moves to the next window and shuts off it’s the last window.

The sensor is a pair of small bare wires epoxied into the rain gutter. It only takes one drop of water to touch between the wires and start the system. I used gold-plated wires (cut from precision resistors) to prevent oxidation.

I built the project assuming I would need DPDT relays, but during installation, I found that SPDT relays were sufficient. In my car, the window motor wires are grounded when no switches are pushed. Check the wiring in your vehicle. You may be able to use smaller relays.

Adjustment:

First, turn R11 (time out) and R17 (stall current sense) fully counter clockwise.  Push the test button and adjust R11 clockwise to the point where the window rolls up completely and waits about a second or two before moving to the next window. Then adjust R17 clockwise to a point just past the point where the system moves to the next window immediately after the previous one is rolled up. You may have to change the value of the current sense resistors (R18, R19 and R20), depending on your car’s window-motor current draw.