Alternator and Regulator Circuit Troubleshooting
- Make sure the battery connections are good and the battery is fully charged (see BATTERY TEST ).
- Remove the engine cover (see step IGNITION COIL REMOVAL/INSTALLATION ).
- Connect a VAT-40 (or equivalent tester), and turn the selector switch to position 1 (starting).
- Start the engine. Hold the engine speed at 3,000 rpm, with no load, until the radiator fan comes on, then let it idle.
- Raise the engine speed to 2,000 rpm, and hold it there.
Is the voltage over 15.1 V?
YES - Replace the alternator (see ALTERNATOR REMOVAL AND INSTALLATION ) or rear housing assembly (see ALTERNATOR OVERHAUL ).
NO - Go to step 6.
- Release the accelerator pedal, and let the engine idle.
- Turn off all the accessories. Select the charging test on the tester.
- Remove the inductive pickup, and zero the ammeter.
- Place the inductive pickup over the B terminal wire of the alternator so the arrow points away from the alternator.
- Raise the engine speed to 2,000 rpm, and hold it there.
Is the voltage less than 13.5 V?
YES - Go to ALTERNATOR CONTROL CIRCUIT TROUBLESHOOTING .
NO - Go to step 11.
- Apply a load with the VAT-40 until the battery voltage drops between 12-13.5 V.
Is the amperage 87.5 A or more?
YES - The charging system is OK.
NOTE: If the charging system indicator is still on, replace the alternator (see ALTERNATOR REMOVAL AND INSTALLATION ).NO - Replace the alternator (see ALTERNATOR REMOVAL AND INSTALLATION ), or repair the alternator (see ALTERNATOR OVERHAUL ).