MS stays powered up with key off

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03-27-2010, 02:58 PM

gianic

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MS stays powered up with key off

It happens once in a while. Cannot figure out what may causing this.
Anybody else had a similar issue?

03-27-2010, 03:15 PM

Ben

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The MegaSquirt ECU does not need a full time powered +12V source, and should not be connected to one. Power up is soley commanded solely by a switched +12V in. If your ECU is not shutting down it is because your switched +12V is not depowering when you turn the key off.

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03-27-2010, 03:19 PM

gianic

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Quote:

Originally Posted by Ben

But it is powered from a switched +12. The same +12 that stock ecu gets.

This is not happening all the time. It happened today. Last time I remember happening was 2 weeks ago and then it was gone until today.

03-27-2010, 03:21 PM

gianic

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Forgot to mention that when this is happening, if I disconnect the main ms harness and then connect it immediately it remains off.

EDIT: From Peter Florance 2009 presentation:

• MS stays powered up with key off.
– Injectors or idle valve not connected to same
switched +12V as MegaSquirt box

03-27-2010, 05:19 PM

yunvmyegt

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bad ignition switch?

03-27-2010, 05:28 PM

Reverant

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Quote:

Originally Posted by Ben

His MS only gets power from 4AF, so +1.

Jim

03-29-2010, 03:09 PM

Matt Cramer

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Any chance the power is back-feeding through a relay?

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03-29-2010, 03:24 PM

hustler

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A friend has this problem too. But when he turns the car to run computer turns off.

03-29-2010, 08:37 PM

yunvmyegt

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and both those symtoms make me still wanna say the ign swtich, my radio used to stay on once in a while, along with something else i forget, but one day the car finally didnt have the start position, and i had to jump it to get to work. but i took apart that switch and the contacts were all begining to melt and just look shitty, so its worth a look....