GO TO ’R’ TERMINAL ON ALTERNATOR
With engine running, measure value of AC voltage
from “R” terminal to “Ground”.
If no AC volts are present, alternator is not
capable of turning on regulator.
NOTE: On a new, first time start up of an
alternator, the alternator may test at less than
5 volts on “R” terminal. The cause of this
problem may be loss of residual magnetism
within the alternator during shipping and han-
dling of the alternator. To restore the residual
magnetism: With engine off and battery
switch on, momentarily (1-2 seconds) con-
nect a jumper wire from ’B+’ terminal to ’E’
terminal. (May spark - this is OK.) Remove
jumper and restart engine. Alternator should
generate properly once the residual magnet-
ism is restored.
• If AC voltage is approximately 14 Volts, alternator
is properly turned on and output of alternator will
be approximately 28 Volts.
If AC voltage is 3 Volts to 5 Volts, alternator is
NOT turned on (regulator is OFF) but alternator
is capable of turning on a GOOD regulator.
NOTE: This test shows only if alternator is capa-
ble of energizing regulator. To check harness
from alternator to regulator go to “Regulator
Connector On Alternator” test.
Continue testing.
Vehicle Charging Circuit Test Is Now Complete:
Remove all jumper wires from alternator used to test
charging circuit.
RE-TEST CHARGING CIRCUIT FOR OPERATION
with ENGINE RUNNING .
Check charging system voltage with engine running.
If no charge voltage, test for voltage at “E”
terminal of alternator, with engine running.
If no voltage on “E” terminal, shut engine down
and inspect link from “R” terminal to “E”.
Run engine and re-test charging circuit.
GO TO REGULATOR (IF REQUIRED)
Disconnect voltage regulator from alternator. There
are no static tests available for the regulator. Continue
test.
GO TO
REGULA
TOR
CONNECTO
R
ON ALTERNATOR
Connect a jumper wire from ground on alternator into
“F-” pin of connector attached to alternator.
Hold a steel wrench or screwdriver near alternator
drive pulley; wrench or screwdriver held near
drive pulley will be attracted to pulley by magnet-
ism.
If there is no attraction, alternator field is de-
fective. Replace alternator.
If there is magnetic attraction, alternator field
is good. Continue test.
With jumper still connected between “B+” terminal and
“E” terminal on alternator: Insert “+” probe of voltmeter
into “E” terminal of connector, and Ground negative
probe of voltmeter to alternator ground terminal.
If meter shows no voltage, alternator is defec-
tive. Replace alternator.
If meter shows battery voltage, circuit is good.
Continue test.
Insert “+” probe of voltmeter into “B” pin in connector.
Insert negative probe of voltmeter into “B-” pin in
connector. (This is power circuit for voltage regulator.)
If circuit shows open (no voltage), alternator
is defective. Replace alternator.
If circuit shows B+ voltage, regulator is de-
fective. Replace REGULATOR ONLY.
NOTE: Turn key and battery switch OFF before install-
ing new regulator. Turn battery switch and key back on
AFTER installing new regulator. Continue test.
Remove all jumper wires from alternator used to test
charging circuit.
Reconnect link from “R” terminal to “E” terminal
B+ F- E B-
METRI-PACK Connector
M13-10 24VDC Electric Supply System M13002 2/99
with 220 Amp. Niehoff Alternator
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