1990 Truck Wiring Problem

[BackyardTech]

I recently converted my old 90 Toy truck from standard to automatic. I changed the wiring under the hood and the computer to accommodate the trans wiring , but later found out that the wiring under the dash is different for the automatic. There's no way I'm going to tackle that, as a result my overdrive cannot be activated. Does anyone know if I can wire the overdrive solenoid directly by connecting a hot wire and ground to it?

You can image the RPMs when I jump on the freeway Any help will be appreciated.