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8A - 4
BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS
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(2) Loose o r w o r n a l t e r n a t o r drive belt.
(3) E l e c t r i c a l loads t h a t exceed t h e output o f the
c h a r g i n g system due t o equipment or accessories i n -
stalled after delivery.
(4) Slow d r i v i n g speeds (heavy traffic conditions) or
prolonged i d l i n g w i t h high-amperage electrical sys-
tems i n use.
(5) Defective electrical circuit or. component caus-
i n g excess I g n i t i o n O f f D r a w (IOD).
(6) Defective c h a r g i n g system.
(7) Defective battery.
MAIN FUSIBLE LINK
CONNECTOR
POSITIVE
TERMINAL
4JL
TEST
INDICATOR
POSITIVE
POST
89BAS
Fig. 6 High Amperage
IOD Test
IGNITION OFF DRAW (IOD)
A n o r m a l vehicle electrical system w i l l draw 5 t o
30 m i l l i a m p e r e s f r o m t h e battery, w i t h the i g n i t i o n
i n t h e O F F position a n d a l l n o n i g n i t i o n controlled
circuits i n proper w o r k i n g order. A vehicle t h a t has
not been operated for a n extended period of t i m e (20
days) m a y discharge t h e battery to a n inadequate
level. I n t h i s case, m a i n fusible l i n k connector should
be disconnected. The m a i n fusible l i n k connector is
located r e a r w a r d of t h e battery on the engine w i r i n g
harness (Fig. 6). I f t h e I O D is excessive (over 30 m i l -
liamperes), t h e defect m u s t be found and corrected.
IGNITION OFF DRAW
TESTS
To test for excessive I O D , verify t h a t a l l electrical
accessories are OFF. T u r n off a l l l i g h t s , remove i g n i -
t i o n key, and close a l l doors and decklid. I f the vehi-
cle
is
equipped
w i t h
electronic
accessories
( i l l u m i n a t e d entry, automatic load leveler, body com-
puter, or h i g h line radio), allow the systems t o auto-
m a t i c a l l y shut off (time out), u p t o 3 minutes.
(1) Raise t h e hood a n d disconnect both battery ca-
bles, negative first.
(2) Connect the negative cable and connect a t y p i -
cal 12-volt test l i g h t (low wattage bulb) between t h e
positive cable clamp a n d the battery positive post
(Fig. 6). Remove the engine compartment lamp bulb.
I f t h e test l i g h t does n o t l i g h t , proceed to step 3. I f
the test l i g h t does l i g h t , proceed to step 4. T h e test
l i g h t w i l l indicate I O D greater t h a n 3 amps.
CAUTION: IOD greater than 3 amps may damage
milliampmeter.
(3) W i t h 12-volt test l i g h t s t i l l connected (not l i t ,
see step 2), connect a n ammeter ( m i l l i a m p e r e scale)
between t h e positive cable clamp a n d t h e b a t t e r y
positive post ( F i g . 7), disconnect test l i g h t , refer t o
instructions provided w i t h ammeter being used. A
r e a d i n g of 30 milliamperes or less indicates n o r m a l
electrical draw. I f ammeter reads more t h a n 30 m i l -
liamperes, excessive I O D m u s t be corrected.
POSITIVE
TERMINAL
AMPMETER
MILLIAMPERE
SCALE'
FELT
BATTERY
TEST
'NEGATIVE INDICATOR
POSITIVE
POST
898Ar6
Fig. 7 Low Amperage
IOD Test
(4) Locate t h e fuse panel and remove fuses or cir-
cuit breakers one a t a t i m e , i f test l i g h t goes out a n d
the reading drops below 30 milliamperes w h e n a cer-
t a i n fuse or circuit breaker is removed, t h a t c i r c u i t
m a y have a defect. Refer t o Group 8 W - W i r i n g D i a -
grams, for component and splice locations.
(5) I f I O D is detected after a l l fuses a n d c i r c u i t
breakers have been removed, disconnect t h e 60-way
connector
a t t h e Single
Board
Engine
C o n t r o l
(SBEC), located outboard of the b a t t e r y , see Group
8D - I g n i t i o n , for more i n f o r m a t i o n .
(6) I f excessive I O D is detected after a l l fused cir-
cuits a n d SBEC have been verified, disconnect t h e
B + t e r m i n a l from t h e alternator. I f reading drops
below 30 milliamperes, r e i n s t a l l a l l fuses and c i r c u i t
breakers, reconnect B + t e r m i n a l a t alternator, r e -
connect battery, and perform alternator diagnostics
as o u t l i n e d i n t h i s group.
(7) I n s t a l l engine compartment l a m p bulb.
OPEN CIRCUIT VOLTAGE TEST
A n open c i r c u i t voltage (no load) test w i l l indicate
the state of charge i n a battery t h a t w i l l endure
(pass) a load test of 50%cold crank r a t i n g , see B a t -
tery Load Test i n t h i s section. I f a battery has a n
open circuit voltage reading of 12.4 volts or greater
and w i l l not endure a load test, i t is defective a n d re-
placement w o u l d be required, see Group 8 B - B a t -
tery/Starter Service for instructions. To test open
circuit voltage, perform the following operation:
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