Operation CHARM: Car repair manuals for everyone.

Alternator No-Load Test

NOTE: Prior to testing, turn headlamps ON for 10-15 seconds to remove battery surface charge. Wait until voltage stabilizes before performing test.

1. Connect Rotunda 88 Digital Multimeter 105-00053, or equivalent.
2. Connect Rotunda 73 Digital Multimeter 105-00051, or equivalent, across battery terminals and record base voltage.
3. Start engine and run at 1500 RPM with no electrical load.
4. Voltage should be 14.1-14.7 volts.
5. If voltage increases, but increase is less than 2.5 volts, perform Load Test. Load Test
6. If voltage does not increase, or increases more than 2.5 volts, perform Output Test. Output Test