In my opinion for my car, Acura Integra 1991, you should check the contact of small electronic board located next to the gear-shift bar. When you shift to choose the location of P,R,N,D,2,1 of gear-box, because just in P, or N postion, you can start your car. For my car, the problem come from all wires that connect this board to the starter, and you only hear a click-sound at the starter because the current is too weak, because of bad-contacts from these all wires. I fix this problem by my-method, I set-up an extra-circuit by using an extra-relay 12VDC. The control signal from CPU will trigger the relay, and the relay-contact will triggers the starter. Now I never get this problem on my car any more.