Oddball Outputs

ECU Outputs: Oddball Outputs

CPU drivers PJ1 and PJ3 are used as outputs. The PJ1 output drives a signal marked 'VSV' on the ECU circuit board. There are driver transistors for this signal, and the software does indeed drive things onto it, but even though VSV goes to the wiring harness connector, there is no wire present in the wiring harness on the other side. Perhaps it has something to do with diagnostics or testing.

Port PJ3 seems to be an 'alive' signal. An examination of the software shows that the main loop will toggle PJ3 every 5 milliseconds or so, but there is no circuitry that actually does anything with the output signal. There is evidence of debug code littered throughout the ECU software, so I figure that this is a very basic "I'm alive" signal that the ECU developers used to tell when the software crashed.

There is also a "HEAT" signal (port PH5) that I believe would be used to drive a heated oxygen sensor. The Aprilia ECU does not use an oxygen sensor though, so this output is not used, and the related components on the circuit board are not present.

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