i have a 79 f150. i replaced the ignition switch and also the starting solenoid. i thought this would accomplish the problem. i just dropped the motor back into the beast, but as soon as i turn the key to the run position it engages the starter. not on the crank postion where it should be. so i dont know. all of my connections are right, went through everything and nothing seems to work out right. so any help would be appreciated.

 

Get a schematic and start checking. Not much else to do. We can't see your truck or trace the wiring. OEM Schematics can be purchased online fairly cheap.

 

Do you have TWO small wires going to the starting solenoid?

Maybe you got them reversed? It's possible that the start OUTPUT at the solenoid is switched to the start INPUT to the solenoid. When you turn on the key, the ballast resistor might feed voltage back to the solenoid.

Not sure if the '79 has the two wires to the solenoid or not.

 

That is why I like the OEM schematics. They give wire colors and you can be reasonably sure they are correct. The schematics in most aftermarket service manuals are kind of generic and of dubious accuracy.

 

I agree, sounds like the wires are crossed. Pull the small single wires off the side of the starter solinoid. With key in run, one should have power. With key in start, other one should have power. The solinoid has 's' over the terminal for wire that's powered in start position, and 'i' over the terminal for the wire that's power in run position. Check that and let us know what you find.

Marty

 

wires arnt crossed, the brown is for the coil and the other, i believe that is red is the ignite wire for the starter. all the wires are hooked up correctly. just dont know.

 

I agree, sounds like the wires are crossed. Pull the small single wires off the side of the starter solinoid. With key in run, one should have power. With key in start, other one should have power.

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I have to question this explanation.

Willow tree

On the starter solenoid there should be 2 small lugs with 90* connnectors on them

They are marked I and S.

When the key is placed in the start position the S terminal gets power from the key to trip the solenoid to crank the starter.
At the same time there should be 12 volts of power at the I terminal which is sent to the coil for extra ooomph in starting the engine.

This means with the key in the start position there shopuld be power to both terminals

When the key is moved to the RUN position the power ceases at the S terminal but the I terminal gets a power feedback to it from the ignition switch/harness.

Unless the new Ignition switch and/or the starter solenoid is faulty, it is my belief that the two wires that run to the two small terminals are crossed.

I'll be back with a pic or illustration.

This is an illustration of the Duraspark II ignition with the starter solenoid only having the one small terminal.That being the S terminal.




By clicking this link you will see the 2 small terminal solenoid used with the old points ignition system,
It shows you how the starting system with the voltage boost at start-up works better.
http://www.clubfte.com/users/mil1ion...ntIgnition.JPG


All the 78/79's I have seen have this set-up with the 2 terminals and having Duraspak II