PSA: I did this modification on a 2019 2520 XLD which has the wire run built in to the the overhead. Not all year Parkers have the wire run so your application may be different.
The stock wiper system is a very basic circuit with a C/B an On Off switch and the wiper motor as can be seen in this drawing.
To install the Marinco 76080 Controller I began by dropping the overhead panel to access the wiring to the motors. I decided the easiest place to mount the controller would be in the overhead space. The controller instructions state the "+" connection should be made to a power source which is powered when the ignition is on. I took that with a grain of salt and decided to use what was already in place. Instead of running more wire I decided to use the preexisting STBD wiper switch (lower of the two) as my switched power and the Port wiper switch (upper of the two) would be replaced with the controller switch.
The wiper motors needed to be loosened from their mount in order to access the fast/slow/park terminals which, as mounted, are on the front of the housing and impossible to access. I removed the 3/8" nut from the bracket and the 3/4" nut on the wiper shaft. This gave me enough room to work. I did not remove the motors completely. Nor did I need to remove the wiper arms.
In the stock configuration my wiper motors were wired to the fast terminal. I used a Power Probe to confirm.
In the overhead the wiring to each motor had a connector plug which I cut out. I crimped a female spade terminal on the "fast" wires on the motors and connected them to the "fast 1+2" connections on the controller.
I joined the ground wires from each motor and the ground wire to the STBD wiper switch, crimped on a female spade terminal and connected them to the "-" connection on the controller.
I crimped a female spade connector on the STBD wiper power wire from the switch and connected it to the "+" connection on the controller.
I had to make four wires of less than 12" in length to connect the "slow" and "park" terminals on the motors to the "slow 1+2" and "park 1+2" on the controller. These (in blue on the next picture) have female spade connections (controller end) and very small ring connectors (motor terminal end) crimped on.
I removed the Port wiper switch (on off) and replaced it with the (on)off(on) switch which came with the controller. I cut the connector in the overhead off and crimped a female spade terminal and connected it to the "switch" connection on the controller. The ground wire from the connection was set aside and not needed.
In this configuration, the Stbd wiper switch arms the system and the new switch (replacement for the Port switch) controls the wipers.
To get the motors to park where I wanted them to (in my case both outboard) I needed to remove the cover plate on the STBD motor remove the two screws and rotate the wheel 180 degrees. Also, as an FYI my wipers are set to 80 degrees of sweep. I tried to change it to 110 degrees; but, the wiper blade would hit the upper edge of the windshield.
This was actually a fun project with great results which took about two hours because of the need to loosen and retighten the wiper motors. Let me know if you have any questions.
