On-Vehicle Testing
- Disconnect battery cables and install cut-out switch, variable resistor, ammeter and voltmeter. See Fig 1. Connect ground cable and ensure cut-out switch is in closed position.
- Start engine and run at 3000-4000 RPM. Adjust variable resistor to following amperage readings. Turn battery cut-out switch to "OFF" position. Set 65-amp alternators to 45 amps and 55-amp alternators to 25 amps. System is okay if voltmeter reads between 12.5-14.5 volts.
- If system does not read correct voltage, substitute a good voltage regulator and repeat test. If correct voltage is still not present, alternator is defective.
Courtesy of VOLKSWAGEN UNITED STATES, INC.