Engine cranks in on position

[69RestoRod]

Reassembling a 69 F100 with a 390 after stripping it to bare bones and am having trouble with the starting system. When the key is turned to the on position the engine starts cranking until I turn the key completely off. Before hadn it would only crank when it was in the on position and you turn the key the extra 1/8 of a turn. Replaced the ignition switch since it seemed like it was shorting internally but no luck.

The solenoid is acting normally because it opens when 12 volts is applied and closes when the 12v is removed.

Any ideas? I've checked the wiring diagrams here but I must be over looking something simple since it worked fine before I tore into it.

[convincor]

Did 69 use both small terminals on the relay??
If so, they may be backwards..
One is 12v for ignition, the other to activate relay.

[convincor]

http://www.fordification.com/images/sch ... rging2.jpg
this diagram shows them both used.
circut 32 and 262 @ the relay
262 will have 12v with key on.
32 should only have 12v when the key is in the start position.

[kaptnkaos]

Hey Jason,

Welcome to the forum...
I've heard of that happening with a bad switch...
Not sure if the two small wires on the cylinoid being switched would cause that or not...
It sounds like it is shooting 12v straight to the starter through with the key.
I know if you bridge one of those with direct positive it will crank even without the key. Which is what is making me think that those wires might be crossed. The key is hot when on and bridges the connections, completing the circuit to send power to the cylinoid and engage the starter.
If it is sending the power to the cylinoid in the on position it would cause it to crank
I'd check to make sure all of the connections at the cylinoid are correct then work your way back to the switch.

KaptnKA S

[seattle67]

Yup, having the two wires that go to the small posts on the starter solenoid swapped would cause the starter to engage as soon as you turn the key to the on position. Looking straight at the two small posts on the solenoid, the wire on the left post should be Red with a Blue stripe, the wire on the right post should be Brown.

Another way to test it, if you cant see the colors on the wire, is by using a meter or a test light. Lift both wires off of the two small posts on the solenoid, turn the key to the on position. With one of your test leads on ground, check for voltage on the two wires, only one should have voltage. That wire should go on the right post. When you turn the key to the start position you should then also get power on the second wire, that wire should go on the left post.

[Hawkrod]

These guys are right about the switched wires causing this. Unfortunately this is a common problem especially because not all companies make the solenoids the same way! These days with offshore companies, some solenoids are actually built backwards. If you look at the solenoid very carefully there will be an S and an I next to the small posts. S is for start and that one gets the red and blue wire. I is for ignition (it is the ignition bypass wire for 12 volts while cranking) and it gets the brown wire. Hope this helps, Hawkrod

[kaptnkaos]

Touche Hawkrod... Good point

KaptnKA S

[seattle67]

some solenoids are actually built backwards

I didn't know that, thanks for the information Hawkrod