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Discussion Starter · #1 ·
So I went to start my mustang this morning to go to work and the starter stuck on.
I turned the key off and removed it, but it was still going, so I disconnected the battery and that's how it sits now.
I haven't had any time to look at it yet, so just preparing checklist.
Car is a manual transmission.

My 2 thoughts are ignition switch or starter solenoid.
Car is 33+ years old, so I know crap is starting to get old.

First, if it was the ignition switch that was sticking (sending power to the small post), wouldn't that stop when I took my foot off the clutch due to the clutch safety switch?
The clutch switch is between the ignition and the solenoid, correct?

Someone mentioned a bad battery could cause it to stick.
Battery is new less than 2 weeks ago...but doesn't rule out that it's not bad.
I'll check datalogs when I get home to see what voltage was during the initial cranking.

My main thought is solenoid.
I'd prefer to get a Motorcraft one, but I don't want to wait the week or so to get one (non in stock locally).
Any 'better' parts store brands?
My thought is to spend a few bucks on a decent auto parts store version and also order the Motorcraft one so I can at least have the car back on the road for the next week.
Yes, throwing some money away doing that, but it won't break the bank.
 

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So I went to start my mustang this morning to go to work and the starter stuck on.
I turned the key off and removed it, but it was still going, so I disconnected the battery and that's how it sits now.
I haven't had any time to look at it yet, so just preparing checklist.
Car is a manual transmission.

My 2 thoughts are ignition switch or starter solenoid.
Car is 33+ years old, so I know crap is starting to get old.

First, if it was the ignition switch that was sticking (sending power to the small post), wouldn't that stop when I took my foot off the clutch due to the clutch safety switch?
The clutch switch is between the ignition and the solenoid, correct?

Someone mentioned a bad battery could cause it to stick.
Battery is new less than 2 weeks ago...but doesn't rule out that it's not bad.
I'll check datalogs when I get home to see what voltage was during the initial cranking.

My main thought is solenoid.
I'd prefer to get a Motorcraft one, but I don't want to wait the week or so to get one (non in stock locally).
Any 'better' parts store brands?
My thought is to spend a few bucks on a decent auto parts store version and also order the Motorcraft one so I can at least have the car back on the road for the next week.
Yes, throwing some money away doing that, but it won't break the bank.
I had the exact same symptom. Changed the solenoid out with a Standard from O'reilly's and havent had an issue since. Would've gone Motorcraft but it wasn't in stock.
 

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Original style starter right?

Pull the small wire off the solenoid and check 12V to ground. You should only have it when the key is turned to crank. Should be a dead wire at all other times. Yes, the clutch switch should interrupt it, but switches fail. It's possible it's failed closed. If you have 12V at all times, something is up with this circuit. If the starter was running, you probably could have pulled this wire off and seen if it stopped.

Use a DMM set to continuity and go across the two posts on the solenoid? You should NOT have continuity unless the relay is closed, which only happens when you have 12V on the small wire on the top post.

Now might be a good time for a 92+ mini starter conversion
 

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Discussion Starter · #4 ·
I had the exact same symptom. Changed the solenoid out with a Standard from O'reilly's and havent had an issue since. Would've gone Motorcraft but it wasn't in stock.
Yeah, no Motorcraft in stock anywhere and I don't want to wait a week+ to get one.
I'll pick up something on my way home.

Original style starter right?

Pull the small wire off the solenoid and check 12V to ground. You should only have it when the key is turned to crank. Should be a dead wire at all other times. Yes, the clutch switch should interrupt it, but switches fail. It's possible it's failed closed. If you have 12V at all times, something is up with this circuit. If the starter was running, you probably could have pulled this wire off and seen if it stopped.

Use a DMM set to continuity and go across the two posts on the solenoid? You should NOT have continuity unless the relay is closed, which only happens when you have 12V on the small wire on the top post.

Now might be a good time for a 92+ mini starter conversion
Yes, original (or at least original style) clunky starter.

I'll do some testing when I get home to check power and continuity before I switch any parts.
When it was cranking, I wasn't thinking about anything other than disconnecting negative battery cable.

I have been thinking about getting a new (92+) starter this year. Maybe I'll just bite the bullet even if I don't need it.
 

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Yeah, this is a common way for the starter solenoid to fail. I had a couple fail this way in my 91 coupe. cheap ones tend to fail faster than the motorcraft ones
 

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Discussion Starter · #6 ·
It was the solenoid.

I disconnected the signal wire and tapped the battery post and it sparked like crazy.
Checked continuity between the posts and they were shorted.

Duralast Gold solenoid in there and cranks just fine....even seems to be a bit stronger cranking, but that might be in my head.

Probably order a Motorcraft replacement this weekend.
 
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