Looks like I can almost say "Welcome to the 4x4Wire..." but you've been logged for some time.

The horns and wipers run through the combination switch on the steering column. I would advise evaluating grounds and relays after a looksee at the FSM (field service manual) available on MitsubishiLinks.com. Download (free) the appropriate manuals in PDF. One of our members hosts that site and is appreciative of donations to keep the site going.

R-