Need help finding a power source.

So my electronic boost gauge needs a power source that is ignition-hot...but it has to STAY hot while the engine is cranking (key in "start" position). This is for the auto calibration function of the gauge.

I can't find anything that fits the bill. Hoping someone with more experience can help me out.

Independent dedicated switched battery line? ECU power line?

Chris

Who makes the boost gauge and what does the instructions say?

Also, aren't the interior lights constant power as well?

Chris

Whatever powers the ECU, fuel pump, ignition would be hot while cranking and while running.

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Originally Posted by Miatamaniac92

Who makes the boost gauge and what does the instructions say?

Also, aren't the interior lights constant power as well?

Chris

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It's an autometer sport comp electronic gauge. Interior lights are constant. I need something that's only on with the key.

Wouldn't ECU be constant hot and not switched? I'll look into fuel pump - that seems to make sense.

Radio?

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Originally Posted by Magma

Radio?

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That's where it's currently wired to. Radio gets no power when the key is in the "start" position.

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Originally Posted by mk2tmr2

Wouldn't ECU be constant hot and not switched? I'll look into fuel pump - that seems to make sense.

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I'm not an expert on the Miata ECU, but my guess would be that there would be two power sources to the ECU - one for keep alive memory, and another to power it, the injectors, and the spark when it needs to be running, sort of like most radios. I could be wrong, though.

Ummm...what about that little blue plug (not sure of the correct name for it) on top of the wheel well on the driver's side? The one you connect to when checking timing? Isn't that one hot?

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Originally Posted by cam76034

Ummm...what about that little blue plug (not sure of the correct name for it) on top of the wheel well on the driver's side? The one you connect to when checking timing? Isn't that one hot?

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Not sure which one you're referring to. I've got a PDF of the full wiring diagram for the whole car now, so I'm sure I'll find something :)

So it looks like the Light Green wire coming from the PCM on connector 3 position N is the signal to the fuel pump relay.

My question is do I tap into this wire for my power source or do I need to go for the Red and Blue (R/L) wire coming out the other side of the relay? I don't have much of a clue how to read these types of diagrams.

http://www.steveandlee.com/galleries...m_fuelpump.gif
http://www.steveandlee.com/galleries...pump_relay.gif

Bueller?