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PWM control for DCCD


Kim Abraham

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Is it possible/advisable to use an unused G3 PWM output as a feed for controlling (basic auto mode) for an early (EMCD) type DCCD. I understand that the amperages required to feed the DCCD would mean you would need some kind interface between the G3 and the diff to isolate it, but the PWM outputs are able to give variable voltages in response to sensor inputs aren't they? Not just on/off type switching.

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By definition PWM is always an ON/OFF signal.  It switches on at a particular frequency and off after a period of time.  It is the on and off times that vary.  Averaged out over time a PWM signal gives the effect of a variable voltage.  The GP PWM channels are not currently enabled, so there is no user configurable PWM channel to do that job at the moment.  I dont know anything about DCCD control so I cant be much use.  Depending on what currents are like a simple transistor circuit is probably all that is needed.

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Ok thanks, this would be why there are stand alone PIC based controllers that read the output from the TPS, G sensor, speed and wheel sensors. Just thought it could be elegant to do it all through a single unit if possible. From what I can gather the DCCD (well the early ones anyway)get moved around by the current supplied (something like 3 amps apparently) with the voltage varying between less than 0.5 to 6 - 7 volts to control lock from 35:65 to 50:50, so it's probably better not to have anything too directly connected to the ECU that is switching that sort of current I suppose.

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