Alternator: Testing and Inspection
PRECAUTION1. Check that the battery cables are connected to the correct terminals.
2. Disconnect the battery cables when the battery is given a quick charge.
3. Do not perform tests with a high voltage insulation resistance tester.
4. Never disconnect the battery while the engine is running.
1. INSPECT DRIVE BELTS
a. Visually check the drive belt for excessive wear, frayed cords etc.
If any defect has been found, replace the drive belt.
HINT: Cracks on the rib side of a drive belt are considered acceptable.
If the drive belt has chunks missing from the ribs, it should be replaced.
b. Using a belt tension gauge, measure the belt tension.
Belt tension gauge:
Nippondenso BTG-20 (95506-00020)
Borroughs No. BT-33-73F
Drive belt tension:
New belt
175 ± 5 lbf
Used belt
115 ± 20 lbf
If the belt tension is not as specified, adjust it.
HINT:
^ "New belt" refers to a belt which has been used less than 5 minutes on a running engine.
^ "Used belt" refers to a belt which has been used on a running engine for 5 minutes or more.
^ After installing a belt, check that it fits properly in the ribbed grooves.
^ Check with your hand to confirm that the belt has not slipped out of the groove on the bottom of the pulley.
^ After installing a new belt, run the engine for about 5 minutes and recheck the belt tension.
2. VISUALLY CHECK GENERATOR WIRING AND LISTEN FOR ABNORMAL NOISES
a. Check that the wiring is in good condition.
b. Check that there is no abnormal noise from the generator while the engine is running.
3. CHECK DISCHARGE WARNING LIGHT CIRCUIT
a. Warm up the engine and then turn it OFF.
b. Turn OFF all accessories.
c. Turn the ignition switch "ON". Check that the discharge warning light is lit.
d. Start the engine. Check that the light goes OFF.
If the light does not go off as specified, troubleshoot the discharge light circuit.
4. INSPECT CHARGING CIRCUIT WITHOUT LOAD
HINT: If a battery/generator tester is available, connect the tester to the charging circuit as per manufacturer's instructions.
Charging circuit test connections:
a. If a tester is not available, connect a voltmeter and ammeter to the charging circuit as follows:
^ Disconnect the wire from terminal B of the generator, and connect it to the negative (-) tester probe of the ammeter.
^ Connect the positive (+) tester probe of the ammeter to terminal B of the generator.
^ Connect the positive (+) tester probe of the voltmeter to terminal B of the generator.
^ Ground the negative (-) tester probe of the voltmeter.
b. Check the charging circuit as follows:
With the engine running from idling to 2,000 rpm, check the reading on the ammeter and voltmeter.
Standard amperage:
10 A or less
Standard voltage:
13.5-15.1 V
If the voltmeter reading is more than standard voltage, replace the voltage regulator.
If the voltmeter reading is less than standard voltage, check the voltage regulator and generator as follows:
^ With terminal F grounded, start the engine and check the voltmeter reading of terminal B.
^ If the voltmeter reading is more than standard voltage, replace the voltage regulator.
^ If the voltmeter reading is less than standard voltage, check the generator.
5. INSPECT CHARGING CIRCUIT WITH LOAD
a. With the engine running at 2,000 rpm, turn on the high beam headlights and place the heater blower switch at "HI".
b. Check the reading on the ammeter.
Standard amperage:
30 A or more
If the ammeter reading is less than the standard amperage, repair the generator.
HINT: If the battery is fully charged, the indication will sometimes be less than standard amperage.