Compo

Starter motor fault

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Posted (edited) · Report post

Evening, following on with the ever depressing starter motor issue, a mechanic I’ve used before has looked at it and tells me I’m getting 12v at the small spade connection on the starter motor when trying to turn the engine over , when the pressure on the ignition key is released this voltage should stop but doesn’t ......so he tells me I have a faulty ignition switch or something else, he also tells me the starter motor is probably stuck in and doesn’t advise bump starting it......I’m at a loss, do I don’t I......it’s a smart four2 2006 plate, we supposedly had the starter motor changed but the date on it matches up with the registration so that sounds a bit iffy.....

Edited by Compo
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Tell him to check the starter switch then, or key switch whichever you wish to call it.  If the switch is working correctly .....

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Posted (edited) · Report post

sounds like it needs a starter...or has a bad connection on the spade terminal

 

 

sounds like garage ripped you off or installed a used starter

 

 

Edited by LooseLugNuts

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The starter is controlled by the ECM/SAM rather than directly from the ignition switch...this is why you're able to use STAR to crank when doing diagnostic tests.

 

This is interesting because I've seen a few examples of where the ECM/SAM over cranks under some situations. Not an issue with the ignition switch or starter. The best guess is that the ECM is not seeing the engine rpm or bump in voltage from the alternator and thinks it needs to keep cranking therefore sending the 12v to the starter signal wire. I've never gotten a chance to find out where the problem lies unfortunately.

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Easiest fix is conventional control of starter. 

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so does it continue cranking engine after it starts?....or does it not crank at all?

 

stating 12v at spade terminal isnt enough info

 

 

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18 hours ago, stickman007 said:

The starter is controlled by the ECM/SAM rather than directly from the ignition switch...this is why you're able to use STAR to crank when doing diagnostic tests.

 

This is interesting because I've seen a few examples of where the ECM/SAM over cranks under some situations. Not an issue with the ignition switch or starter. The best guess is that the ECM is not seeing the engine rpm or bump in voltage from the alternator and thinks it needs to keep cranking therefore sending the 12v to the starter signal wire. I've never gotten a chance to find out where the problem lies unfortunately.

Take out SAM and open it up carefully and look under micro lenses for cold solder joints over the entire board front and back....just for starters....so to speak....Use a solder sucker and electronic circuit board solder not pumbing solder to resolder the bad solder joints. Also use a smaller soldering iron with fine tip so you do not over heat circuit board.   Just my bent nickel's worth of info......lol

 

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i will be following along on this discussion,  my smart overcranks.  but not all the time.  

its no big issue yet,  it will only over crank for about 3 seconds then as Stickman said above,  the SAM just tells the starter to stop cranking.

 

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i just had to blip the key on mine...it would crank on its own until it started

 

so power at the terminal for a bit after key is released sounds normal

 

but if its not cranking with 12v present its the starter or a bad connection

 

for overcranking i would use a test light and verify if its caused by 12v crank signal or by sticking solenoid

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