It usually means that your alternator (or generator) is not charging the battery. At this point you need to check system voltage with a voltmeter when the engine is running. You should see at least 13.5 to 14.5 volts. If it is less than that, it is not charging. You can also have the charging checked at a repair shop if you don't have a voltmeter.
If it is your voltmeter that drops while the vehicle is running. Most likely the alternator isn't putting out enough volts.
Pull the hot (+) positive lead on the battery while running...If car quits it's bad. Best way is to put voltmeter (Multimeter) on battery while running..if 13 + volts at idle then alternator is good, if 14+ then it's great!
Check with a voltmeter connected to the battery Voltage with engine running should be approx. 13.8-14.2 volts- above this could be a defective voltage regulator
Either the battery is weak and not charging properly, the connections are dirty on the terminals of the battery or the alternator is not putting out enough power. If you rev up the van does it go out or is it on while you are driving?
A 2000 Chevy Venture might skip while driving because of water in the fuel or damaged or dirty fuel injectors. You might also have an issue with the distributor.
The alternator may not be charging it enough. With the engine running at an idle check the voltage at the battery with a DC digital voltmeter. It should read from 13.5 to 15.5 Volts. Anymore, or any less, and the alternator is suspect. You might also have a defective battery.
You will need a digital voltmeter. Set the voltmeter to 20 volts DC. Check it with the probes. 1. 12.68 Volts = 100% Charge2. 12.45 Volts = 75% 3. 12.24 Volts = 50%4. 12.06 Volts = 25%5. 11.89 Volts... You can also put the digital volt meter across the positive and negative terminals of the battery, while the car is running. The reading should be no less than 12.5 volts dc, and no higher than 15 volts. If it higher than 15 volts the regulator is overcharging your battery, and it will boil the fluid in the battery. Some regulators are on the chassis of the vehicle, most are built into the brush assembly of the alternator. Either change the alternator or consult your nearest auto shop for a new brush set and regulator.
There could be a few reasons why a 2000 Chevy Impala shuts off while driving. There could be a problem with the fuel pump, a bad spark plug, or even a loose battery cable.
put a voltmeter on the battery and test voltage, then start the cycle and check again. A battery at rest should be at about 13 volts, with the engine running it will be at 14 or above. to be sure disconnect the positive battery terminal while running, if there is still good volts there, or the engine does not die it is ok.
Probably fuel pump failure.
fuel pump might be going out