I have a 1975 F-250 and I've had it for a few months and I've been restoring it. Ive put up a LMC headliner with speakers in my truck and now every time I put the key in the ignition to the AUX works fine but the when I tern the key to the right the starter is constantly turning all I did with the headliner was connect the speaker wires to the radio, not sure what the problem is but if anyone has advice I'd be much appreciated.

I've got a new whole ignition tumbler thinking that was the problem but it wasn't.

 

Just a new tumbler, or a whole new switch and tumbler?

 

X2 on I bet you need a new switch (the part that the elec connector plugs into behind the dash).

 

Yes I got a whole new switch and tumbler is what I meant.

 

Did you unhook any wiring/elec connectors under the hood before the headliner install?

Sounds like a stuck starter solenoid (the one mounted on the inner fenderwell).

 

​​​​​​Not that I would know of that is why I am so confused because the day this problem happened I started it to let it warm up in the morning and the truck had no problems then when I started it in the afternoon that's when this started happening. Maybe the starter solenoid is no good?

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Ok so no wiring disconnect under the hood and maybe reconnected incorrectly. I'd guess starter solenoid on firewall or yes solenoid on the starter itself.

And the new ignition switch/tumblers went in no problem? Electrical connector for the switch is ok? And no PO wiring messed with behind the dash in the area of the ignition switch?

 

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New ignition switch and tumbler went in perfect, Electrical connector is like new, and wiring behind the dash in the area of the ignition switch is all good.

 

I've got a new starter solenoid and the ignition is still making the starter turn constantly.

 

Sounds like you have a wiring issue some where for sure then. Here is some discussion between a fellow FTE member with an elec issue and mikeo0o0o0 and FMC assisting him. Its long, but might help.

"Some of those earlier models had a starter solenoid with 2 small terminals one should say I “ignition” and the other is stamped with an S, that way the coil will get power while cranking and power will stay when the key is released. Use your DVOM and check for power to the coil with just the key on. They used resistors of some sort to cut the voltage down at the coil after cranking, and during cranking you should get a full 12.6 or somewhere about. Once the engine starts the resistor cuts down the voltage to 10-12 so you don't burn out the coil. You need to trace the wire that powers up the coil with the key on.

(MIKE) With the key "on" check for voltage at the coil + terminal. If you show voltage, next, disconnect the battery cable that goes from the solenoid to the starter. This is just so the starter doesn't turn over. Now, turn the ignition to the "start" position and check for voltage at the + coil terminal. If you show voltage there, I would suspect four possibilities. First, the solenoid, Second, a wiring problem. Ford uses a resistor wire and these do sometimes go bad. It's rare but it does happen. These can be "wired around" by using a regular ceramic resistor wired parallel to the original circuit. Third, a bad ignition switch and Fourth a bad ignition module.

(REPLY) With battery at 12.3v, coil at "run" has 6.47v, at "start" has 11.9v next step, please?

(MIKE)If you have a test light, touch it to the negative terminal of the coil and crank the engine. It should blink as the engine turns over. While you're there, check the resistance between the - and + coil terminals, it should be less than 1 ohm.

(FMC) The fact that the coil voltage drops in RUN means that both the coil and module are getting powered properly - the drop in RUN tells you that the module is grounding the coil at a stand-still, as it should.

(FMC)In addition to what Mike has described (which will help isolate the problem to either the primary or secondary sides), check the resistance between the ORANGE and PURPLE wires coming from the distributor. It should be between 400 and 700 ohms. Neither wire should have continuity against the BLACK wire (total of three measurements). Often times, if the pickup fails (which is what you're checking), it will not switch the module while the engine is cranking, but letting off the key collapses the coil, which gives that final spark. If the BLINK test BLINKs, then my test is a moot point.

The results of the testing
1. Light BLINKED as starter turned engine over
2. 1.5ohm across coil terminals
3. 647ohm across ORANGE and PURPLE wires from dist
4. DMM read "OPEN" ORANGE to BLACK and PURPLE to BLACK

(REPLY) On #2, at first I could not get a reading that was stable for 10 or 15 seconds until it finally settled to 2.8ohm. I cleaned the terminals with scotch brite and that dropped the time to immediate and measurement to the reported number. Dist was replaced 2 yrs ago because vac adv mech was corroded and locked up, along with plugs and wires, when I got the truck running. Coil and ign module remain as purchased from PO.

(FMC) All of your observations (1 through 4) are perfect. They tell you that the entire primary side of the ignition system is in perfect working order. If there is no spark in the presence of these conditions, then the problem is isolated to the secondary side - distributor cap, rotor, wires, or plugs. Note, however, that these items have no "sense" of the position of the key, so a problem there would not correlate to your original observations (only get spark when you let off the key). In other words, your two sets of observations can't co-exist, so something changed, or is missing from the story."

 

Unplug the red wire from the "S" post on the solenoid fender relay, and it should open the secondary circuit, which powers the starter.

Did you fasten the switch to the dash? It might need a ground if it's just hanging by the wires.

 

Do you mean the starter relay/solenoid was changed AFTER this problem started, or you had replaced it recently for some other reason?
If before, try throwing the old one back on. The new ones are very often junk.

In fact, starter relays are probably the most problematic new part for any model vehicle anywhere. They just fail so often it's scary. Most are within the first couple of starts to about a week at the most. If you can get a new starter relay past the first month, you're doing good!

Also, one way to test the theory of it being a bad relay/solenoid/thingy or the ignition switch wiring, is to pull the Red w/blue wire (the "S" wire) off of the relay while it's cranking uncontrolled.
So the next time it sticks and keeps the starter spinning, pull the small "S" wire. If it stops the starter from spinning, then the problem is before the relay.
If the starter continues to crank/spin, then the starter relay is faulty.

Even if you changed a bad one out for a new one, you can't rule out the new one being a double fault. Gotta' check them things still.

Good luck.

Paul

 

Good point, but while some functions need the switch grounded, the main ones (START, ACC and RUN power) do not. They're simple open/close circuits, so grounding is not needed.

Paul

 

Some more FTE discussion/troubleshooting.

https://www.ford-trucks.com/forums/8...-problems.html

"Engine cranks with key in "run" position" thread: https://www.ford-trucks.com/forums/7...-position.html

 

Ok I found the problem and it was that the starter solenoid was wired wrong and because of that it must have caused one of my fuses to blow out. Thank you guys for your help I wouldn't have figured this out without the help.