Possible, but in general there is ussually a pull up resistor inside the engine ECU that detects if the MAF is unplugged, unpowered etc.
If the MAF was not powered then I personally don't understand how it would have "some voltage down it" (that wasn't generated by the engine ECU and hence would be known of by the engine ECU...)
I would have thought MAF unpowered would appear in a similar fashion to MAF open circuit , but perhaps not

Interesting anyway
FYI: On the later model Toyota engines that I've played with you can bridge the diag pin Tc to E1 to get the check engine light to flash in the normal fashion.
Cheers
Wilbo
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