Preparing for the test
Before starting the test, perform the following checks and, if necessary, repair faulty parts and assemblies.
Check the condition of the battery installed in the vehicle.
Note. The battery used for this test should be slightly discharged. The load generated by a fully charged battery is not suitable for this test to be carried out accurately.
Check alternator drive belt tension.
Turn the ignition key to position «OFF».
Disconnect the wire from the negative (–) battery terminals.
Disconnect the standard wire from the output «IN» generator.
Connect ammeter (DC, with a range of 0-100 A) in series between output «IN» generator and its standard wire. Make sure the wire (–) ammeter is connected to a standard wire disconnected from the generator.
Note. Securely and tightly fasten each connection, as a large current will be supplied to the terminals. Do not use clamps (type «crocodile») when connected to an electrical circuit.
Pic. 7.11. Generator output current test circuit
Connect Voltmeter (with a scale of 0–20 V) between output «IN» generator and «weight». Connect (+) voltmeter lead to terminal «IN» generator and then (–) voltmeter wire to a suitable «mass» (to the body) (pic. 7.11).
Connect a control tachometer according to the manufacturer's instructions. Connect the wire to (–) battery terminal.
Leave the engine hood open.
Verification procedure
Make sure the voltmeter shows battery voltage. If the voltmeter shows 0 V, then either an open circuit has occurred between the output «IN» generator and (-) battery terminal, or the fusible link is burned out, or there is a poor connection with «weight».
Start the engine and turn on the headlights.
Turn on the high beam headlights and set the heater fan switch to the position «HIGH», then sharply increase the engine speed to 2500 min-1 and read the maximum value of the generator output current (indicated by an ammeter).
Note. After starting the engine, the charging current drops rapidly. Carry out the test as soon as possible in order to have time to measure the maximum value of the generator output current.
Analysis of results
The ammeter reading must be above the limit value. If the ammeter reading is below the limit value, and the output circuit «B» generator is serviceable, remove the generator from the car and check it on the stand.
Maximum allowable value:
- generator 75 A - minimum 52.5 A.
- generator 90 A - minimum 63.0 A.
Note. The rated recoil force of the generator is stamped on a plate affixed to the generator housing.
Note. The value of the output current varies depending on the load on the generator and the temperature of the generator case, so the rated output force may not be achieved. In such cases, to increase the electrical load (in order to discharge the battery) turn on the high beam headlights for a while or connect the exterior lighting system of another car.
Note. The rated value of the generator output current may also not be obtained as a result of overheating of the generator housing or too high ambient temperature. In such cases, let the generator cool down and retest.
After checking the generator output current, gradually reduce the engine speed to idle, then turn off the ignition.
Disconnect the wire from the negative (–) battery terminals.
Remove the ammeter, voltmeter and control tachometer.
Connect the standard wire to the output «IN» generator.
Connect the wire to the negative (–) battery terminal.