Alternator and Regulator Circuit Troubleshooting
Alternator and Regulator Circuit Troubleshooting1. Make sure the battery connections are good, and that the battery is sufficiently charged.
2. Raise the vehicle on the hoist to full height.
3. Hook up the ammeter, 0-400 A, to the starter subharness.
4. Lower the vehicle on the hoist.
5. Hook up the voltmeter, 0-20 V (accurate within 0.1 V), to T101.
6. Start the engine. Hold the engine speed at 3,000 rpm, with no load until the radiator fan comes on, then let it idle.
7. Raise the engine speed to 2,000 rpm and hold it there.
8. Turn on the headlights to high beam, and measure the voltage at the under-hood fuse/relay box terminal.
Is the voltage between 13.9 and 15.1 V?
YES - Go to step 9.
NO - Replace the alternator or repair the alternator.
9. Read the amperage at 13.5 V.
NOTE: Adjust the voltage by turning on the blower motor, rear window defogger, brake lights, etc.
Is the amperage 60 A or more?
YES - Alternator/regulator operation is OK. Go to alternator control circuit troubleshooting. Alternator Control Circuit Troubleshooting
NO - Replace the alternator or repair the alternator.