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2003 Miata Main Relay ground

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Old 08-05-2016, 12:05 AM
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Default 2003 Miata Main Relay ground
Diagnosing a MSPNPPro (MM01-05). The main relay isn't turning on.

Looking at the 2003 diagram it looks like the ECU is supposed to ground out the relay and turn it on. Yet in Franks MS3 guides, and on this ECU, pin 3H (the one connected to the main relay) does nothing.

Car works fine if you ground out the main relay manually.

Is there some undocumented feature of the stock ECU that triggers the main relay?






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Old 08-05-2016, 09:57 AM
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Yes. Check to be sure that you're getting 12V power on pin E16 with the key on. This tells the MSPNP Pro to turn on the main relay.
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Old 08-06-2016, 06:39 PM
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Originally Posted by Matt Cramer
Yes. Check to be sure that you're getting 12V power on pin E16 with the key on. This tells the MSPNP Pro to turn on the main relay.
Pin E16? Which one is that?

Also, is this documented anywhere? Or did you guys just figure it out when making one?

I'm surprised Frank's pinout doesn't have anything related to it.
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Old 08-09-2016, 01:48 PM
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Heard back from Matt. Here is the spreadsheet that maps the ecu pins to the NP122 connector



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Old 08-09-2016, 08:43 PM
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Replaced Q1 on the adapter board. Was a 2N2222a, only had a 2n4401. But it seems to work.

Will test on the car later.
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