Ford LRG-423 Service Manual page 187

03-78
Auxiliary Systems
03-78
GENERATOR DIAGNOSIS AND TESTING (Continued)
PINPOINTTEST
E:
INDICATOR LAMP
OFF, KEY ON, ENGINE NOT RUNNING (Continued)
TEST STEP RESULT
b ACTION TO TAKE
1 E4 1 CHECKS CIRCUIT WIRING
I
SERVICE Circuit 4 (W/BK).
Circuit should be hot only
when engine is running.
CHECK for swapped wires
in voltage regulator
connector.
GO to E5.
Yes
b
l
Remove one-pin S connector from generator.
l
Measure voltage at wiring harness S terminal, Circuit 4
(W/BK).
l
Is voltage greater than 0 volts?
I No
b
1 E5 1 CHECK FOR SHORTED RECTIFIER
I
Yes
If lamp is on with one-pin S
connector removed,
REPLACE generator.
REPLACE voltage regulator.
l
Measure voltage at the S terminal on the back of the
generator.
l
Is voltage greater than I volt? No
b
PINPOINTTEST F: GENERATOR NOISY
I
TEST STEP
RESULT
ACTION TO TAKE
I
Fl 1 CHECK FOR ACCESSORY-DRIVE NOISE
l
Check the drive belt to make sure that it is installed
properly and is not damaged.
l
Check the accessory mounting brackets for loose bolts
or out of alignment condition.
l
Check for a bent pulley.
l
Is accessory drive OK?
Yes
No
GO to F2.
SERVICE accessory drive
as required.
I
F2 1 SUBSTITUTE KNOWN GOOD GENERATOR
Yes
b
No
b
Generator is OK. INSTALL
original part. CHECK other
accessories to find the
cause of the noise.
REPLACE generator.
l
Remove generator and replace with a known good
generator.
l
Is noise present with known good part?
PINPOINT TEST G: RADIO INTERFERENCE
TEST STEP RESULT b
Gl
1
VERIFY RADIO INTERFERENCE
ACTION TO TAKE
Generator is OK.
Interference is occurring
elsewhere in the electrical
system.
GO to G2.
l
Start engine. Yes
b
l
Tune radio to a station where interference is present.
l
Remove three-pin voltage regulator connector.
l
Is interference present with connector removed?
No
b
G2 1 SUBSTITUTE KNOWN GOOD GENERATOR
Yes
No
b
Generator is OK.
Interference is occurring
elsewhere in the electrical
system.
REPLACE generator.
l
Remove generator and replace with a known good
generator.
l
Is interference present with known good part?
PINPOINTTEST H: INDICATOR LAMP ON, KEY OFF
TEST STEP
RESULT b ACTION TO TAKE
HI 1 CHECK LAMP CIRCUIT WIRING
l
Turn key to OFF position.
l
Remove three-pin voltage regulator connector.
l
Measure voltage at wiring harness I terminal, Circuit
904 (LG/R).
l
Is voltage greater than 0 volts?
Yes
No
b
SERVICE Circuit 904
(LG/R). Circuit should be hot
in RUN position only.
SERVICE instrumentation
system. Indicator lamp
circuit is finding a path to
ground at a point other than
the generator.