Well, kinda need to know if it did anything else. If the vehicle continued operating at normal, probably a fault voltage gauge or regulator. If you actually lost all power, the whole thing would shut down.
If it was a temporary loss of power, then it kicked back to normal, you're probably looking at a loose or faulty ground wire.
A short in the turn signal wiring can cause the voltage gauge to fluctuate. A loose ground wire can also cause the gauge to fluctuate.
13.5-14.5 volts.
13.5-14.5 when running.
low coolant
Perhaps a defective voltage regulator- not regulating voltage Perhaps a defective gauge-
Possible bad alternator.
Is it low on Gas or Deisel? if it is that will trip the check gauge light. Or if you ever run the fuel low. It needs time to reset it self.
Several things can cause your fuel gauge not to work. The most common cause is a bad ground wire. A malfunctioning float in the fuel tank can also cause the problem.
Either the gauge or the voltage regulator device on the charging system has failed.
The voltage does not depend on the gauge of the wire, but on the thickness and type of insulation.
The relay sensor is likely defective
The voltage gauge on the Blazer is not the most accurate (cheap) When using the signals the voltage draw on the system is enough to make the gauge move slightly.