Car wont cut off...

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lexluger

Member
Joined
Feb 13, 2015
Messages
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Location
Lexington ky
My Car
1972 mustang 302
I just bought a 72 coupe 302... Engine bay is very clean, anyway the guy told me it needed a new battery so I bought one thinking that would be the cure all. I was wrong, first of all when the key is turned to the OFF position the car alternator remains on. I have to turn the key between off and start to get the car to be fully off but I can't remove key in this position obviously. Sometimes the car turns over but most of the time it doesn't... seems like it drains the battery immediately. I had the battery and alternator tested and both were good. After doing some research I found out that the starter solenoid goes bad on these cars often... I changed that out as well but I'm still having issues. Any help would be appreciated. My next guess would be the ignition coil then the ignition switch. I've read similar situations but I'd like to get this whipped before I keep replacing good parts... thanks in advance

 
I think that I would look at the ignition switch before the coil. If it's an automatic the neutral safety switch may also need adjusting. Hard to diagnose without being able to check things out with a meter.

 
I think your problem is in the ignition switch itself but the starter relay is definately worth checking out. You might try testing the different posts on the starter relay with a digital multimeter and see what is going on there in relation to key position. The ignition switch is fairly easy to change out but make sure you get the right one based on vehicle production date. Good luck. Oops jbojo beat me to it on the submit button lol.

 
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first i would change the ignition switch.

pop the pos connector on the battery.

you need to drop the steering column to gain access the switch is mounted to the top of the steering column.

there are 4 large nuts under the steering column that hold it up to the dash board frame.

first there are 2 Phillips head screws that secure the plastic part of the column to the instrument cluster panel.

pop the screws then pop the 4 nuts. and slowly lower the column to the drivers seat make sure nothing is catching or you missed a screw or bolt.

on top of the column is the switch, there will be a small linkage from the key tumbler to the switch. pop that off and unplug the connector and pull the switch.

turn the the key all the way back so you can push the new switch all the way forward(opposite of engine start position with spring) push the linkage into the switch then align it.

tighten the screws and test the switch in all 4 positions. ACC only/off/ Run/ Start.

reassemble the column and battery and test.

 
Welcome to the board! I hate electrical problems but have gotten pretty good with a multi-meter. Do you have a multi meter and know how to use it?

A little clarification on what you posted will help.

I was wrong, first of all when the key is turned to the OFF position the car alternator remains on.
Do you mean the car keeps running or you believe current continues to pass through the alternator?

I have to turn the key between off and start to get the car to be fully off but I can't remove key in this position obviously. Sometimes the car turns over but most of the time it doesn't... seems like it drains the battery immediately.
When you say 'fully off' what do you mean? Are you saying this is what you do to get the car to stop running? Are you moving the key from 'off' to 'start'? The car not running over symptom happens when you are having trouble turning it off or all of the time?

Before you pull the ignition switch let's confirm you are wired correctly at the starter solenoid. It is easy to swap the two small wires and it will cause strange results. There are 4 posts total, two large and two small. The small one near the battery gets power from the ignition switch when you are in the 'start' position. It energizes the solenoid and completes the circuit to the large post that is furthest away from the battery. This goes to your starter. At the same time it also completes the circuit the to the other small post. This goes to your coil and provides non-restricted current to the coil during cranking. Once the engine starts the circuit to the starter and the coil is opened. The coil continues to get power via a resistor wire.

With a multi-meter confirm voltage at the battery. I should be close to 12v when the car is not running.

Determine which of the two small wires gets approximately the same voltage(about 12v) when the ignition switch is in the 'start' position and only in the start position.

The other wire may indicate voltage while the car is in the 'run' position but it should be less than 12v if a previous owner did not remove the resistor wire.

The wire that only has voltage while in the 'start' (crank) position goes to the small terminal on the solenoid that is closest to the battery. If you look closely it might have a 's' indicator. The other wire goes to the other side, if you look close there might be an 'i' indicator on the solenoid.

Here is a picture I found of the solenoid.

56317d1340581640-ford-4-terminal-solenoid-wiring.jpg


Once you have confirmed this see if your problems continue. If they do, then try removing the wire from the 'I' terminal and see if that fixes your problem (for trouble shooting purposes)

Does the engine look modified? Can you tell if there is an new/aftermarket coil? Does it look like someone has rewired the engine compartment?

 
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I appreciate the help fellas... Will heres what I have at the solenoid... the small post close to the battery has two terminals on it one looks like it leads inside the cabin (ignition switch) the other is inside conduit but if I was a guessing man it looks like its going to the alternator. May be why the alternator is always energized. I'm going to remove it and see if it fixes my issue but seems like I'll cause another because that wire will need to go somewhere.

 
Interesting. There are not many reasons why there would be an additional wire would be included on the small post next to the battery. One possible reasons is if you have an electric fuel pump and a oil pressure safety switch. Even then, I would have put it on the "I" side, not the "S" side. (We can discuss how such a safety switch works if you confirm you have an electric fuel pump).

When I ran fuel injection I had a wire going to the ecu so the system knew I was cranking the engine. I may have put that one on the "I" side. But generally you would add a wire there to detect that the engine is being cranked.

But yes, in the mean time remove that second wire and see if that fixes your problem.

 
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I removed the second wire but the alternator remained on... so i removed all the wires from the big post closets to the battery with the + wire running to it and no more alternator. Now I need to figure out which one is the alternator and which post it should go on. One wire is labeled linkage fuse??? I'm going to do some research to figure out where is an acceptable post for each wire.

 
When the ignition is in the off position where I can remove the key event is still running. Lights, heat etc... worth no key and in the off position... That's why my battery keeps being drained. In order to turn the car off (nothing running) I have to turn it between the off and start position.

 
I'd pull out the lock and cylinder(where the key goes in) and inspect the cylinder for proper operation and then also verify that the end portion seats correctly when you put it back in. If that is worn or broken, it can slip and not push/pull the actuating arm when the key is being turned.

That would be where I'd start before changing the electrical portion of the ignition switch. Usually if you turn the key and the car doesn't start or stop, the lock and cylinder is not working properly. They tumbler could be stripped and while the key position looks to be in off, it could very well likely be in the run position.

To me this would be more likely them the ignition switch mounted on the column. I would completely scratch the starter solenoid out of the equation though. If the car is starting, the solenoid is working and to be honest, they really don't fail all that often.

I'd set my focus on the lock and cylinder. Best of luck!

 
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