2. Replace the generator if the test results are negative. See "Generator" in the Vehicle Maintenance section. If it passes the test, perform the power output test on the vehicle as follows.
Important: Always check the generator output before assuming that the generator is faulty due to a short to ground at the "L" terminal.
3. Connect a digital multimeter (a), ammeter (b) and a carbon bar resistor to the vehicle's battery (d) and alternator (e).
Important: Make sure the battery is fully charged and the carbon film resistor is disconnected.
4. With the ignition switch off, check and record the battery voltage.
5. Remove the wiring harness connector from the generator.
6. Turn the ignition switch to the ON position with the engine not running. Use a digital multimeter to check the voltage at the "L" terminal of the cable harness connector.
7. The reading should be approximately equal to the specified 12 V battery voltage. If the voltage is too low, check the "L" terminal circuit for shorts to ground and open circuits that could cause a voltage drop. Correct open wires, terminal connections, etc., if necessary. Follow step "Charging system" in this section.
8. Connect the generator wire harness connector.
9. Run the engine at medium idle speed and measure the voltage between the battery terminals. The reading should be greater than the reading recorded in step 4, but less than 15 volts. If the reading is greater than 15 volts or less than the previously recorded reading, replace the alternator. See "Generator" in the "Car maintenance" section.
10. Start the engine at medium idle speed and measure the generator output current.
11. Connect the carbon film resistor and adjust it to get maximum current when the battery voltage is above 13V.
12. If the reading is within 15 amps of the alternator rating, the alternator is OK. Otherwise, replace the alternator. See "Generator" in the "Car maintenance" section.
13. With the generator running at maximum output, measure the voltage between the generator case and the negative battery terminal. The voltage drop should be 0.5 V or less. If the voltage drop is greater than 0.5 V, check the connection between the generator case and the negative battery terminal.
14. Check, clean, tighten and recheck all ground connections.
(The text of the article was obtained from the website: «chevyman»)