Check For Shorted Rectifier; Check For Open Stator Phase; Indicator Lamp On, Engine Running - Ford LRG-423 Service Manual

GENERATOR DIAGNOSIS AND TESTING (Continued)
PINPOINTTEST A: DEAD BATTERY/NO GENERATOR OUTPUT (Continued)
TEST STEP
A8

CHECK FOR SHORTED RECTIFIER

Remove one-pin S connector from generator.
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Measure voltage between the S terminal on the back 01
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the generator and ground.
Measure voltage between the positive (+) battery
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terminal and the S terminal on the back of the
generator.
Is either voltage reading greater than 1 volt?
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A9
Install S connector.
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Start engine.
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Turn on headlights or any accessory.
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With engine running at 2000 RPM, measure voltage
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drop between the B+ terminal on the back of the
generator and the positive (+) battery post.
Is voltage drop less than 0.5 volt?
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CHECK FOR OPEN STATOR PHASE

A10
Connect test point F on the voltage regulator to the
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negative (-) battery post using a jumper wire.
Repeat Generator Output Test.
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Is generator output greater than the minimum
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output specified?
A l l
Remove generator.
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Remove voltage regulator.
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Measure resistance between the generator slip rings.
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Is resistance greater than 10 ohms OR less than 1
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ohm?
TEST STEP
Measure voltage at test point A on the voltage
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regulator.
Is voltage at test point A equal to battery voltage?
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B2
Remove three-pin voltage regulator connector.
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Turn key to ON position.
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Is indicator lamp on?
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Install voltage regulator connector.
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Remove one-pin S connector.
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Connect wiring harness S terminal, Circuit 4 (W/BK) to
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the positive (+) battery post using a jumper wire.
Is indicator lamp on?
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Remove three-pin voltage regulator connector.
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Measure wiring resistance between the one-pin S
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connector and the S (center) pin of the voltage
regulator connector.
Is resistance greater than 1 ohm?
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Auxiliary Systems
PINPOINTTEST B: INDICATOR LAMP ON, ENGINE RUNNING
RESULT
Yes
No
Yes
No
Yes
No
Yes
No
RESULT
Yes
No
Yes
No
Yes
No
Yes
No
ACTION TO TAKE
REPLACE generator.
GO to A9.
GO to AlO.
REPAIR excess voltage drop
in Circuits 38, 290, and 37.
CHECK fuse link in Circuits
38,290, and 37 and the
connections between the
battery and under-hood fuse
box.
REPLACE voltage regulator
REPLACE generator.
REPLACE generator.
CHECK for worn brushes
(less than 8mm long) or
open brush leads and
REPLACE if required. If OK,
REPLACE voltage regulator
ACTION TO TAKE
GO to B2.
CHECK fuse or fuse link in
Circuit 36 and REPLACE if
required. If OK, REPAIR
open in Circuit 36 (Y/w).
REPAIR short to ground in
Circuit 904 (LG/R).
GO to B3.
REMOVE jumper wire. GO
to B4.
REMOVE jumper wire. GO
to B5.
REPAIR open or excess
resistance in Circuit 4
CHECK for loose or bent pin
in voltage regulator or
connector. If OK, REPLACE
voltage regulator.