Wipers are Outputs 12A, 12B, & 12C on the Vansco "PDM" which is on the interior of firewall, ahead of passenger's feet, behind the plastic kick panel. Remove the panel (velcro) and you should see the #12 LED light up w/output signal to the wipers. If nothing there, try rebooting it by turning chassis battery disconnect Off (switch @ battery compartment), then back On. Retry wipers.
Then, for further misdirection, report your results here.
Baja-tested '08 2-slide 36'
Alpine: The Ultimate DIY'er Project