Chuck , make sure all grounds are good. There are ground wires under the car and in the engine compartment. Disconnect and clean with some light sandpaper and tighten, alot of the relays close on ground contact which is very important to having electric circuit run properly. I am not sure if a faulty
engine harness will keep car from starting, but it probably will not run correctly if there are shorts. Environmental controls etc. might be messed up.
Good Luck Dave