Generator Test

Generator Test (Undercharged Battery Check)
This condition, as evidenced by slow cranking or low specific gravity can be caused by one or more of the following conditions even though indicator lamp may be operating normal. Following procedure also applies to cars with voltmeter and ammeter.
- Make sure that undercharged condition has not been caused by accessories left on for extended period of time.
- Check drive belt for proper tension.
- If battery defect is suspected, refer to "Battery Description:".
- Inspect wiring for defects. Check all connections for tightness and cleanliness, battery cable connections at battery, starting motor and ignition ground cable.




No-load Check
1. Connect voltmeter and ammeter as shown in the figure.

NOTE: Use fully charged battery.

2. Run engine from idling up to 2,000 rpm with all accessories turned off and read meters.
If voltage is higher than standard value, check ground of brush.
If brush is not grounded, replace IC regulator.
If voltage is lower than standard value, proceed to following check.

Specification for undercharged battery (No-load check)
Current: 10 A
Voltage: 14.4 - 15.0 V (at 20 °C, 68 °F)






NOTE: Consideration should be taken that voltage will differ somewhat with regulator case temperature as shown in the figure.

3. Ground "F" terminal and start engine, then measure voltage at "B" terminal
- Voltage is higher than standard value it is considered that generator itself is good but IC regulator has been damaged, replace IC regulator.




- Voltage is lower than standard value it is considered that generator itself has problem, check the generator.

Load Check
1. Run engine at 2,000 rpm and turn on head light and heater motor.
2. Measure current and if it is less than 30 A, repair or replace generator.

Generator Test (Overcharged Battery Check)
1. To determine battery condition, refer to "Battery Description:".
2. If obvious overcharged condition exists as evidenced by excessive spewing of electrolyte, measure generator B terminal voltage at engine 2000 rpm.
3. If measured voltage is higher than upper limit value, disassemble generator.




4. Check ground of brush. If brush is not grounded, replace IC regulator. Then check field coil for grounds and shorts.