just went thru this with my 73 challenger, here's what it was for me... first off the boot plug that connects to the ecu is very tight fitting, making it hard to connect... the screw and nut that hold it in were in a psition that made it hard to put boot on completely, so I readjusted the nut and spread out the openeng to allow complete contact and only put the screw in after plug was seated... next my starter relay was faulty, the voltage drop was preventing the 9.4 volts from getting to the coil during starting... also key must be used during starting as there is a seperate wire from the switch (brown I believe) that bypasses the ballast resistor during cranking ( key in starting posistion). I'd imagine you can hot wire t straight to the ballast as others have mentioned. I learned all of this from this group and am very greatful for all of the responses I have received!