15: Install the alternator using the two mounting bolts and reattach the serpentine belt. Reconnect the negative battery cable and start the vehicle. Let it idle for 10 to 15 minutes to allow the voltage to stabilize. Check the voltage and ensure that it's registering approximately 13.5 to 15.1 volts. Stop the engine and re-check belt tension and ensure that the alternator mounting bolts are tight.