Ok I have an 81 camaro z-28 I installed a new starter now for some reason it doesn't start everytime I turn the key. I tested voltage from battery reads same as battery voltage. Also tested with a helper voltage on key signal side only have half voltage? I removed the wire retested same way I have 12 volts but when hooked up on starter I only have half? I have replaced neutral safety switch and ignition switch no change any suggestion on what issue may be?