1966 mustang wants to start when key is in the on position and s

i rebuilr engine put all together and a freind hooks ground cable to starter side so may have damaged something. I then replaced - Starter, Solenoid and put new battery in and now it tries to start in on position. The switch was tocuhy before all this as it stuck at times before the rebuild? is ti the switch and how does it come out?  

first... UNPLUG both small wires from the starter solenoid...

that should stop the cranking...

next grab your test light or circuit tester

with a friend in the drivers seat...

hook the test lead clip to the negative battery...     have them turn the key to the ON position...    you should have power on only ONE of the 2 push on wires...   that one goes on the stud marked I    (i)

the other one will have power only when the key is in the cranking position... not in the ON position..

this wire should go on the S terminal of the starter solenoid..

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what the wires on the starter solenoid do.

the wire on the S terminal comes from the ignition switch  cranking position.. but it comes out the firewall and down to the neutral safety switch  where it is only allowed to continue if the transmission is in Park or Neutral... then back up through the firewall . continuing under the dash board.. through the harness around to the starter relay S terminal..

the wire on the I terminal is also hooked to the ignition coil positive...  under the dash.. just behind the ignition switch there is a resistance wire.. travels across inside an over jacket.. connects to the harness just before it passes through the firewall.. this reduces the ignition coil voltage so the points don't burn out..    from inside the harness ..  this wire extends to the I terminal on the starter solenoid.. with the reduced voltage...

ONLY during cranking.. does the I terminal contact inside the solenoid make contact with the contact disc.. this sends full battery voltage to the coil positive to give you a hotter spark for cranking....

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things that CAN FAIL on fords... cause the car to crank when the key is in the RUN and in the crank position..


#1   push on terminals installed in the wrong position at the starter solenoid...  see test above..

#2.  wiring running down to the neutral safety has lost its insulation and shorted out to he other pair that carries power for the back up light circuit....

2b..  neutral safety switch wiring harness was NOT secured to the side of the transmission .. allowed to flap in the wind under the car... fatigued the wiring and the insulation to the point of where the wires where they pass through the strain relief into the neutral safety switch are touching...

3#   problems with the wiring at the ignition switch...  

66mustang68:
i rebuilr engine put all together and a freind hooks ground cable to starter side so may have damaged something. I then replaced - Starter, Solenoid and put new battery in and now it tries to start in on position. The switch was tocuhy before all this as it stuck at times before the rebuild? is ti the switch and how does it come out?

To replace the switch, you put your key it and move it to the ACC position. There is a small hole in the key cyl you insert a paper clip end into to remove the key cyl from the switch and turn CCW a little more. The dash bezel holds the switch onto the das h- you turn the switch to release the switch from the bezel. If you find after doing Waynes t/s'ing procedure you need to replace the switch, that's how you do it.

Heres a adequate youtube video on how to do it.
http://www.youtube.com/watch?v=tCMLzQaiUB0