Quote:
Originally Posted by wstar
It's possible, but that would make the service manual wrong. The chart listed there is intended to be "what you see with a probe" on that line, and apparently it's 0V when it's been unlocked for 15+ seconds, 12V when it's locked (or recently unlocked), and then a signal a little negative pulse signal against a 12V background for the lock/unlock command. What makes no sense in that chart is: how does the BCM send the pulses against 12V to lock from the unlocked state, if the line is at 0V? :P Clearly, at the very least the chart just doesn't tell the whole story, but it does seem it's 12V and unlikely serial, just some timed pulses.
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This is common in the electronic world. The line is "pulled up" to the signal voltage (most electronics in the consumer world use 3.3V or 5V) and then switched to ground to send data pulses. Like you said this doesn't look like complicated data, just a simple pulse pattern with fixed frequency.