Generator Test (Undercharged Battery Check)
This condition, as evidenced by slow cranking or indicator clear with red dot can be caused by one or more of the following conditions even though indicator lamp may be operating normal. The following procedure also applies to vehicles 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:M13A
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.
Use fully charged battery.
1. Generator
2. Ammeter (between generator “B” terminal and battery (+) terminal)
3. Voltmeter (between generator “B” terminal and ground)
4. Battery
5. Load
6. Switch
2) Run engine from idling up to 2,000 rpm and with all accessories turned off read meters.
If voltage is higher than standard value, check ground of brushes.
If brushes are not ground, replace IC regulator.
If voltage is below or in standard value, proceed to the following check.
Specification for undercharged battery (No-load check)
Current: 10 A
Voltage: 14.2 – 14.8 V at Hi (H) (at 25 °C, 77 °F)
Voltage: 12.5 – 13.1 V at Lo (L) (at 25 °C, 77 °F)
Consideration should be taken that voltage will differ somewhat with regulator case temperature as shown in the figure.
[A]: Regulated voltage (V)
[B]: Heatsink temperature (°C)
3) Ground “F” terminal and start engine, then measure voltage at “B” terminal as shown in the figure.
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
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 20 A, repair or replace generator.