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Not a stupid question at all. When I first built the OBDuino I just assumed it was ISO9141, I didn't actually check until it didn't work! Anyway, the two grounds the K line and the batt are the only pins populated in the connector under the dash. When I scope the K-line with the car off it hovers at 5V, when the car is 'on' or the engine is running I see 12v on the K -line. When I plug in the obduino I see s a few slow (~5Hz) bits go by followed by some faster bits, then nothing. This makes me think that the wiring etc is correct (I have checked it twice) and that at least the transmit function of the MC33290 is working.
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