mgmuscari

I have an '89 5.0

This fall I had to replace the starter solenoid because there was dead short inside it (after heavy rain) and the car just plain would not start. I was in a pinch so I replaced it with a "ProStart" solenoid from Pep Boys (I hate the quality of their stuff, but I figure... it's basically just a switch, how bad can it be?)

The other night there was a lot of rain, and after driving in it for a while, I stopped for some errands. Upon starting the car, the starter just kept cranking after I released the key from the "Start" position. I panicked and turned the key to "Off," but it kept cranking anyway!

I figured, "OK, another shorted solenoid." I had someone drive me to Pep Boys (again ) and picked up another one. I swapped it out standing in the rain in the CVS parking lot, and the car started up fine.

Today is a beautiful sunny day, bone dry, not a bit of moisture anywhere. I just stopped somewhere and came back out to start the car - yet again, the starter just kept cranking even after I turned the key off. I yanked the negative battery cable, and reconnected it after a minute. The car started up fine.

So at this point I think I've eliminated the solenoid from the equation, but I'm a little confused now - the only reason I can think of for this to be happening would be if the solenoid is still getting a hot signal to keep the switch closed.

I don't have a circuit diagram with me (I'm "home" for the holidays). Can somebody who is familiar with this circuit confirm that the only way this could be happening would be a failing key cylinder?

I would like to avoid burning out my starter or destroying my flywheel if at all possible - so far it hasn't died and just keeps cranking the engine.

Much obliged.

AdderMk2

ignition switch in the column... very common. The next time you try to start the car, do so with the hood open. when it continues to crank, pull the small single wire off the solenoid, if the car stops cranking, the switch in the column is the problem

mgmuscari

Thanks, that's what I was thinking it was.

I'll boldface my questions here so that people can skip the fluff if they want.

After disconnecting the starter from the solenoid I sat and played with it for a while... I connected my multimeter to the starter terminal on the solenoid and tried turning the key a bunch of times... I couldn't reproduce it. This looks to be a very intermittent problem for now but I'm going to try to fix it soon. How difficult is it to open up the steering column and replace the switch? Should I just capitulate and take it to a shop for that? I like doing things myself but I can't afford to be without my car for more than a day...

Thanks for pointing out that I can just yank the little wire off to stop it... duh, why didn't I think of that?

Does the computer do anything weird while the ignition switch is in the "crank" position that would make it bad to run the car while it's on? (i.e. if I pull that wire to disengage the starter)

AdderMk2

nope....

Jfsram

I would confirm this but either pulling the wire while it's cranking on it's own or check for voltage with a test light WAY before you start ripping the column apart.

FLcracker9

Run the test like they said previously. If it's not the ignition switch, it's still in your solenoid. I had the "exact" same problem on my F150. I put 4 or 5 solenoids on it, all from the local auto parts stores, it would work fine for a couple of days, then do the same thing. I finally bought one from Ford, it hasn't done it since (7 - 8 months). The solenoid engaged when I turned the key, but the contacts stayed closed when I turned off the key.

mjr46

if it ends up being a ign switch, just drop the column down for easier access, remove all panels from underneath and around key switch and it'll be alot easier to access

philyoosays

should try replacing the starter relay before you go do anything else. What happens with them is the magnetic switch doesn't let go of its magnetism when the current is gone and it holds the magnetism for a while. As long as the switch doesn't release, you'll keep cranking regardless of what your ignition switch is doing. When you remove the negative end of the battery, and give it a few minutes, you're allowing the magnetism to leave the switch. In a bad relay anyways....

It's worth a try, changing the relay vs. any additional work

mgmuscari

i was on my third solenoid a few days ago when the starter decided to go ahead and engage under POWER this time. i was getting on it in 2nd gear, around 3500rpm when the starter just kicked in... needless to say it self destructed.

fortunately for me the teeth on the starter's gear are weaker than the flywheel - they flattened out like pancakes but the flywheel wasn't damaged at all.

after i pulled off the road and pulled the battery cable again, i tested the starter power cable with my multimeter and found it was grounded. as near as i can figure there was an intermittent short in it that was somehow causing the solenoid to engage without a hot input signal.

i replaced the starter and the problem seems to be gone - ah well, i was thinking about replacing the starter anyway.

jwstangs2005

Hi, I have a 1990 Mustang GT. At first it would not start so replaced the starter, starter relay, ignition switch, and ignition cylinder. Now the car tries to start without the key everytime we attempt to hook up the battery. At first I thought that the new relay might be bad so I replaced the new one, same problem. Is it possible that we might have gotten a bad one 2 times in a row? Could the starter or relay be installed incorrectly? I took every wire except the positive cable and cable running to the starter off and it still did the same thing. Am I correct in thinking that this means that it is not the ignition switch or ignition cylinder? Thanks.