1966 f-100 with a 390 and c6 3 spd auto w/ shifter on column. (390/c6 installed by PO.)

The truck had been running great, but now I turn the key and nothing happens when in the start position. If I go to the ON position the warning lights come on in the dash. When I move the key to START, . . . nothing at all.

- This happens in PARK, NEUTRAL, or any gear position so I don't think it's a Neutral Safety Switch adjustment . . . maybe faulty all together?

- The battery is good.

- The engine is not frozen or stuck I can manually turn it over

- If I jump over the starter solenoid the starter cranks.

- The starter solenoid does not seem to be getting any current to either of the smaller screws when key is in the START position.

- There is a post on the back of the ignition switch that gets juice when in the ON position. I crawled under and was able to see a couple of other wires not attached to that post, and they do not seem to be getting a current when I turn the key . . . if I checked correctly.

Not sure where to go from here.

 

As not knowing if N S switch on column or side of trans. Go to and remove it. See if a tang that moves it when the shift lever is operated may be broken. While off test the switch SAFELY, meaning don't try to start unless you are POSITIVE THE TRANS IS IN PARK. With harness disconnected from the switch and using a test light, and a helper if needed, check all the terminals. 1st with key off, 2nd with key on and 3rd with ignition switch held in the start position. If one of the terms has power in start position, I'd say the ignition switch and wiring thru there is OK. Now maybe try a jumper from the hot wire when in start position to one of the other wires in the connector and see if the engine cranks. If yes, I'd say bad switch

 

Sure sounds like the S terminal of the starter solenoid is not getting power, so you're on the right track. Do you have power at the start terminal of the ignition switch when you have the key turned to start? If you do, then disconnect the S terminal at the solenoid and start testing for voltage from the switch through the N S switch and on to the solenoid. I'm sure you'll either find a bad switch or a bad/broken wire somewhere in there.

There is also the possibility that the solenoid contacts are no longer working. If you have access to another known working solenoid it would be a pretty quick component test to install it. This would only be a possibility if you are getting full voltage at the S terminal when the key is in the Start position.

 

Your replies are very helpful in pointing me towards my next troubleshooting steps. I may have some snow to deal with instead of working on this today, but will follow your advice. The truck is pretty much put away for the winter but I like to start it every week. Thanks again!!

 

It was the neutral safety switch. I bypassed it and was able to start it up no problem. I ordered a new one because do not feel safe keeping the truck without it.

 

Glad you found it, and thanks for posting what the problem was!

 

Thanks for your help. I always like posting the end result because these forums are like an archive of solutions. Hopefully someone can benefit from this thread at some point.