[atrain0007]

Hi all,

Yesterday I was about to take the car out and I realized I forgot something in the house. The car was running so I turned the key to the off position and it continued to run...

The ignition seems to be working to engage the starter and power on and off the accessories (the radio comes onwhen I turn it right and left- on and accessory).

Im not exactly sure how to test where the fault is. A bad ignition switch was my first guess, but the above information makes me think the ignition switch is not bad.

I have a voltage meter. I dont know the ignition system really well, but I thought I should not have power on the positive side of the coil without the key on. Right now I'm getting a full 12v on the positive terminal without the key in there. Does that confirm its a bad ignition switch? I have pertonix electronic ignition instead of points/condenser.

Any other places where I should test for voltage to rule out other components? Thanks in advance.

 

[atrain0007]

additional information

Here is what I'm seeing with the ignition switch on off:
- About 12v on the positive terminal of the coil
- About 12v on the I terminal (little one on the right) of the Solenoid
- No voltage on the starter side of the solenoid
- No voltage on the S terminal (little one on the left) of the Solenoid

I thought I should not have power on the positive side of the coil without the key on... Solenoid issue?

 

[MustangBradley]

The engine is killed whenever power is removed from the coil. Since you have power there no matter what the switch position, you must have a faulty switch. Voltage must be removed from the resistor wire when the switch is in the off position.

 

[thetvirus]

Most likely it is the starter solenoid getting stuck, I would replace that first, it is cheap and fast to install, and it is a common problem.

 

[rex1965]

Pull the I terminal off the solonoid and see what happens to the 12v on the coil, if it goes away, then the solonoid is bad, if the voltage is still there it is getting there from somewhere else, could be ignition switch or a wire shorted to another contact on the ignition switch. Good Luck.

 

[Joes72/65]

If you have 12v on the "I" terminal with the key off, your starter solenoid is definitely bad. I have had this problem in the past also. It is a very high failure rate item. (Thankfully they are cheap and easy! I always have a spare at home.)

 

[MustangBradley]

It is my understanding that the coil gets 12v from the solenoid only when the motor is cranking, so that the coil gets more juice for easier starting. Then when the key is released to the RUN position, the coil is fed approximately 9v via the pink resistor wire. Is my understanding wrong? I am merely seeking knowledge.

 

[Joes72/65]

That's how it's supposed to work. What happened to mine was that the solenoid battery terminal was internally shorted to the "I" terminal, so there was always 12v to the coil. (I knew something was wrong long before I tried to shut the car off because it made my Rally-Pac tach go all wonky!)

 

[MustangBradley]

That's how it's supposed to work. What happened to mine was that the solenoid battery terminal was internally shorted to the "I" terminal, so there was always 12v to the coil. (I knew something was wrong long before I tried to shut the car off because it made my Rally-Pac tach go all wonky!)

I love reading these forums just to glean the little tidbits. I've never run into what you are describing, but now I'll know what to look for if it ever happens to me.

 

[atrain0007]

Thanks for the responses. I'll confirm that works.

 

[atrain0007]

Replaced the solenoid. End of story. Thanks again everyone.