Wiper Motor Project


Pulse wipers stopped working one day. I found the original switch wiring was aged and had a few damaged wires so I replaced it. Still didn't work.. Now to replace the module... except I could not find them, it seems the aftermarket no longer makes the pulse boards... This lead me down the path of searching for options. I found a company made a nice kit, uses the same wiper motor as pictured below, but does not use the factory wiper switch on the column, they use a custom switch that is a replacement for the 81-84 style, wiper switch on the cluster trim panel. This led me down the path of making my own module.

The process was long, learning how to write code and the trouble shooting was also frustrating, but rewarding at the same time. Also learning how to use Eagle PCB software was frustrating, but YouTube tutorials really go a long way.

Initial wiring setup using factory 1987 style wiper switch, Arduino Uno and an 5v 10a relay board (for testing purposes):


Function test showing the 1987 Wiper Switch, Park, Low and High, and 2 delay speeds

1987 Wiper Switch Function testing

Initial function test of OBS 89 Style Wiper Switch, Park, Low and High, Delay. The GMT400 / OBS wiper switch is a 3 wire switch and it uses different resistor values that sends different voltages to the factory wiper module. While it will bolt up to the 1987 style tilt column, it will not work without a custom module, or retrofit the OBS wiper assembly. The wiper switch has a detent / click feeling when going through delay speeds which is what I like and what I will be using, however it works with the factory switch too. The 1987 style switch does not have detents, its like a potentiometer or similar... not sure but no clicks when changing delay speeds, not even a new replacement switch

Video is displayed upside down :(

GMT400 Wiper Switch Function testing

4/2020 Update! Finally tested on my truck using the factory wiper motor!

GMT400 Wiper Switch Function with the stock motor

First prototype boards worked great, except I forgot to include mounting holes..
2nd prototype board included the mounting holes, an LED to to indicate when the switch not in Park for trouble shooting purposes and is a little smaller. I am working on 3rd version to include a fuse holder to hold a 5x20mm 500mA fuse. This project only uses about 420mA of power... so we will see if the fuse size needs to be changed... easy to swap out fuses.


Pictured above is an in progress shot of the Wiper Module and a 3d printed base.
8 pin connector on the left will connect to the wiper switch. The stock wiper switch connector gets de-pinned (and will be reused later), and new terminals crimped on.
12 pin connector on the right will connect to the 3 relays, Low, High and Washer pump.
The output from the relays will have OEM male terminals to connect to the previously removed wiper switch connector and then will connect to the factory wiper connector to control wiper motor and washer pump.
1 separate wire to fuse box to power module

Under the hood, there is one simple modification to the wiring:
1) De-pin B of the 2 pin wiper motor, cut the terminal off and heat shrink it to seal it from the elements.
2) Install new wire with proper terminals and connect to Ground source (for the Park Switch).


This is how I plan on it being be laid out. The wiper connectors about in line with each. Maybe make a sheet metal clip that connects all 3 connectors and clips onto the factory steering column bracket like OE... not sure on that one...This arrangement would allow the module to be tucked away on one side, and the 3 relay harness (incomplete and currently in prototype mode) to be tucked away on the other side. Lastly connect power and ground

*both versions of the board sends the 5v power from regulator to the VIN pin of the Arduino Nano. While it works, I found out later it is not correct, the 5V should be going to the 5V+ of the Nano.... this is also apart of V3 board.

If interested in one of these functional prototype boards, 6$ shipped. you will also need an Arduino Nano with the wiper program loaded on it + components. Send me an email if interested.

E-mail link