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Help with building your Speeduino, installing it, getting it to run etc.
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As described in my post, I would suggest sending the Speeduino IGN signal to G. Try leaving W disconnected (no ground, no high). Set for Spark Output Triggers > going low. This will have the IGN high signal causing dwell and IGN low causing spark to fire. That should be the best configuration for a GM 4-pin as a controlled coil driver, at least with all the ones I've used. <shrug>
By Torslund
Since I don't know what inside the modul I just put a pull up resistor to G and ground it with a transistor, when breaker contact ground transistor it makes the G high and I got spark. W is grounded all time. So I get a square wave pulse to modul and car runs on that. Right or wrong I don't know :)
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The trigger edge setting is only for how Speeduino handles the signal, and does not affect if it produces an output resulting in spark.

By scartail
I agree guys, not knowing the guts of the module is hard. I'm not advanced enough to poke and prod this module to figure out.

Is there anything i should do on the bench before, putting it on the motor? I rather burn out the module than the speeduino.
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Not to worry, as this is an output with little chance of burning something when using the GM 4-pin as a coil driver. That said and for giggles, connect B+ to B, and ground to the mounting hole. Nothing else connected. Put a meter set for continuity from C to ground. It should read no continuity. Apply 5V (from the Speeduino 5V pin or a board 5V source) to G. Terminal C should now show continuity. Don't forget in all of this, that the ground for the module and for Speeduino must be shared (same source or grounds connected).

Likewise, you can connect it all as it will be in the vehicle (except coil), and use the Hardware Test mode in TunerStudio. Again test terminal C for state change when the signal is sent by Speeduino.

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