When I turn the key the lights on the inside of the car turn on and so does the radio. But I don’t get any power to the dash. The car won’t start or even try. I have checked all fuses, replaced the ignition wiring harness, the starter and the battery.

 

When you say "I don't get any power to the dash" are you meaning just that the key won't operate the starter, or that there are also no dashboard lights working? Possibly the neutral/park switch on the shifter?

By the way, this is a Chevrolet forum, but you have posted in the Venture mini-van section.