Alternator Output Test

1. On Sprint, connect battery/alternator tester according to manufacturer's instructions. Ground alternator "F" (full field) terminal. See Fig 3. Maximum alternator output should be indicated by test equipment.
2. On Spectrum, set alternator tester switch to 12-volt position. Connect alternator harness to tester. See Fig 1. Connect White/Red wire to alternator harness.
   Fig 1: Chevrolet Spectrum Alternator Tester Hook-Up

   Courtesy of GENERAL MOTORS CORP.
3. Connect harness to alternator "L" wire (White/Red). Connect Black alligator clip to negative battery terminal. Connect Red alligator clip to positive battery terminal.
4. Turn ignition switch to "ON" position. Check instrument panel charge indicator light. Start and run engine at 1500 RPM. Turn headlights on low beam. After 10 seconds, check lights on alternator tester. Tester will indicate alternator condition. See Fig 2.

Fig 2: Alternator Tester Diagnostic Charts

On all models, set ohmmeter to x100 ohm scale. Check for continuity between terminals "B" and "F". There should be continuity in one direction only.

Fig 3: Exploded View of Spectrum & Sprint Alternators Honda, Isuzu, and Toyota alternators are similar. Courtesy of General Motors Corp.