Alternator No-Load Test
- Ensure battery is fully charged and main fusible link is okay. Turn ignition on. Ensure alternator charge indicator light comes on. If charge indicator light comes on, go to step 3). If charge indicator light does not come on, go to next step.
- Disconnect alternator connector. If charge indicator light comes on, check alternator diodes. If charge indicator light does not come on, check charge indicator light relay and replace if necessary.
- Start engine and allow it to idle. Check charge indicator light. If charge indicator light comes on and stays on, go to step 4). If charge indicator light flickers on and off, check positive alternator diodes. If charge indicator light goes off, go to step 6).
Courtesy of ISUZU MOTOR CO.
Courtesy of ISUZU MOTOR CO.
- Turn ignition off. Disconnect alternator connector. Connect jumper wire between alternator connector terminal "L" and positive battery terminal. See Fig 2.
- If charge indicator light does not come on, replace IC regulator and check alternator rotor and brushes. If charge indicator light comes on, replace charge indicator light relay.
- If charge indicator light goes off when engine is started, check charging system voltage at battery. Connect positive voltmeter lead to positive battery terminal and negative lead to ground.
- Increase engine speed to 1500 RPM and check charging system voltage. If charging system voltage is greater than 15.5 volts, replace IC voltage regulator. If charging system voltage is 13.0-15.0 volts, system is okay.