Charging System Diagnosis P72

1. Check the belt for wear and tension. Refer to Accessory Drive Belt in Engine Mechanical.
2. With the ignition switch ON and the engine off, the lamp should be on. If not, disconnect the electrical connector at the generator and use a fused jumper wire to ground the "L" terminal lead.

•	If the lamp lights, replace the generator.

•	If the lamp does not light, locate the open circuit between the grounding lead and the ignition switch. The lamp may be open.

3. With the ignition ON and the engine running at moderate speed, the lamp should be off. If not, stop the engine, turn the ignition switch ON and disconnect the electrical connector at the generator.

•	If the lamp goes out, replace the generator.

•	If the lamp stays on, check for a grounded "L" terminal wire in the harness.

4. If the battery is undercharged or overcharged, or if the vehicle voltmeter shows high or low voltage with the engine running, perform the following steps.

4.1.	Disconnect the electrical connector from the generator.

4.2.

With the ignition switch ON and the engine off, connect the voltmeter between the ground and the "L" terminal in the wiring harness and between the ground and the "I" terminal, if used. The wiring harness may connect to either "I" or to both terminals. A zero reading indicates an open circuit between the terminal and the battery. Repair as necessary.

4.3.	Connect the electrical connector to the generator and run the engine at moderate speed with all accessories off.

4.4.	Measure the voltage across the battery. If the voltage is above 16 volts, replace the generator.

4.5.	With the engine off, connect an ammeter at the generator output terminal. The ammeter must have the capability to measure at least 15 amps above the generator rating. Connect the ammeter across the generator and a carbon pile across the battery.

•	Run the engine at moderate speed and load the battery with the carbon pile in order to obtain the maximum amperage. Maintain a voltage at 13 volts or above.

•	If the output is within 15 amperes of the rated output, the generator is OK. Refer to Generator Usage.

•	If the output is not within 15 amperes of the rated output, replace the generator.

Charging System Diagnosis P92

1. Check the "turn-on" circuit by performing the following steps.

1.1.	Turn the ignition switch ON.

1.2.	Check the voltage from "To Key Switch" terminal to the negative output terminal.

1.3.	A minimum of two volts should be present. If at least two volts are not present, check the ignition switch and the associated wiring.

2. Check the sensing and field excitation circuit by connecting a voltmeter across the "To #1 Term. of DUVAC" and the negative output terminals. The voltmeter should read the battery voltage.
3. Disconnect the battery ground cable.
4. Remove the regulator from the holder far enough to expose the two contact pads.

If corrosion or dirt is found, clean the contact pads with #600 (or finer) grade sandpaper.

5. Remove and inspect the brushes.

If the brushes appear burned, cracked or broken, or if they are worn to a length of 4.76250 mm (3/16 in) or less, replace the brushes.

6. Check the shunt lead within the brush spring.

If the shunt lead is broken, install new brushes.

7. Clean the brush contact caps with #600 (or finer) grade sandpaper.
8. Reinstall the brushes and the regulator.
9. Reconnect the battery ground cable.
10. Perform the generator electrical test. Refer to Generator Electrical Test.