Check can be performed with alternator installed on vehicle or on test stand.
Caution
If performing check using test stand vacuum pump receives no lubrication; remove vacuum pump - see operation.
Inspect
Battery – fully charged.
Drive belt condition and tension – satisfactory.
Ground connections for alternator engine body battery – satisfactory.
Battery terminal – tight unbroken not oxidised.
Caution
Do not reverse polarity of alternator terminals.
Do not short circuit alternator terminals.
Do not run alternator with battery disconnected (diodes may be destroyed).
Circuit diagram for alternator output check
| 1 | Load resistor variable | 5 | Switch |
|---|---|---|---|
| 2 | Battery | 6 | Charge telltale |
| 3 | Voltmeter | 7 | Alternator |
| 4 | Ammeter | 8 | Charge relay |
Remove
Ground cable from battery.
Install
Ammeter between terminal B of alternator and cable to terminal B.
Variable load resistor across battery terminals – ensure resistor is set to maximum resistance.
Voltage across battery terminals.
Oscilloscope – in accordance with manufacturer's instructions.
Tachometer.
Ground cable to battery.
Caution
Do not set load resistor to minimum resistance at this stage.
Start engine or run alternator.
Measure
Current and voltage:
- 4JA1T engine - 50 A at 5 000 rpm.
- 4JA1TC engine - 60 A at 5 000 rpm.
- 4JG2T engine - 60 A at 6 000 rpm.
Adjust variable load resistor if required current is not attained.
Inspect
Voltage curves on oscilloscope for uniformity.
If required current is not attained or voltage curves appears as peaks and troughs overhaul or replace alternator.
