10.22
ELECTRICAL
Charging System Alternator Tests
Three tests can be performed using a multi-meter to determine
the condition of the stator (alternator).
TEST 1: Resistance Value of Each Stator Leg
1. Measure the resistance value of each of the three stator
legs: Y1 to Y2, Y1 to Y3, and Y2 to Y3.
Each test should measure: 0.19Ω ± 15%
NOTE: If there are any significant variations in ohm
readings between the three legs it is an indication
that one of the three stator legs maybe weak or
failed.
TEST 2: Resistance Value of Each Stator Leg to Ground
1. Measure the resistance value of each of the stator legs to
ground: Y1 to Ground, Y2 to Ground, Y3 to Ground.
Each test should measure: Open Line (OL)
NOTE: Any measurement other than Infinity (open)
will indicate a failed or shorted stator leg.
TEST 3: Measure AC Voltage Output of Each Stator Leg at
Charging RPM
1. Set the selector dial to measure AC Voltage.
2. Start the engine and let it idle.
3. While holding the engine at a specified RPM, separately
measure the voltage across each ‘leg’ of the stator by
connecting the meter leads to the wires leading from the
alternator (Y1 to Y2, Y1 to Y3, Y2 to Y3).
4. Refer to the following table for approximate AC Voltage
readings according to RPM. Test each leg at the specified
RPM in the table.
Example: The alternator current output reading should be
approximately 18 VAC at 1300 RPM between each ‘leg’.
NOTE: If one or more of the stator leg output AC
voltage varies significantly from the specified value,
the stator may need to be replaced.
Test
Connect Meter
Leads To:
Ohms Reading
Battery Charge Coil Y1 to Y2 0.19Ω ± 15%
Battery Charge Coil Y1 to Y3 0.19Ω ± 15%
Battery Charge Coil Y2 to Y3 0.19Ω ± 15%
Test
Connect Meter
Leads To:
Ohms Reading
Battery Charge Coil
Y1, Y2, or Y3
to Ground
Open Line
(Infinity)
Y1
Y2
Y3
RPM Reading AC Voltage (VAC) Reading
1300 18 VAC ± 25 %
3000 42 VAC ± 25 %
5000 64 VAC ± 25 %
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