Also check your physical connections under the dash for the speed control switch and on the wiper motor itself. My 86 (no delay) had the wiring harness changed before I got it and only worked on low speed, also the blades would not return to park when shut off. Come to find out the harness...
I just swapped a Holley Sniper system on my 86 C10 with a 454 last year, this was formerly a carbed 305 truck. I don't believe the FiTech is much different in the aspect it will control all the same things as the Holley depending on how you decide to wire it and the parameters you chose in their...