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8A - 16
BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS
•
RESULTS
(1) I f reading is less t h a n specified a n d a l t e r n a t o r
o u t p u t w i r e resistance is not excessive, t h e a l t e r n a t o r
should be replaced see, Group 8C - A l t e r n a t o r Ser-
vice for i n f o r m a t i o n .
(2) A f t e r c u r r e n t output test i s completed reduce
engine speed, t u r n off carbon p i l e and t u r n off i g n i -
t i o n switch.
(3) Disconnect b a t t e r y negative cable.
(4) Remove test ammeter, voltmeter, tachometer
and carbon p i l e .
(5) Remove J u m p e r W i r e (Fig. 2).
(6) Connect alternator o u t p u t w i r e t o alternator
B A T t e r m i n a l post. T i g h t e n n u t t o 5-6 N-m (45-75 i n .
lbs.).
(7) Connect b a t t e r y negative cable.
(8) Connect a i r hose between Engine Controller
and a i r cleaner.
(9) Use D R B I I t o erase f a u l t code.
CASE GROUND
FIELD
TERMINALS
BATTERY
VOLTAGE
L
-J2-DB-
ALTERNATOR
CASE
GROUND
ALTERNATOR
BATTERY
TERMINAL
ENGINE
CONTROLLER
JUMPER WIRE
TO GROUND
TEST
TEST
AMMETER
VOLTMETER
DISCONNECTED
ALTERNATOR
OUTPUT
WIRE
IGNITION SWITCH
CARBON PILE
RHEOSTAT
CHASSIS ~
GROUND
J908A-13
Fig. 2 Alternator Current Output Test (Typical)
USING ON-BOARD DIAGNOSTIC SYSTEM
OPERATION
OF ON-BOARD
DIAGNOSTIC
SYSTEM
The Engine Controller monitors c r i t i c a l i n p u t and
o u t p u t circuits o f the charging system m a k i n g sure
they are okay. Some are checked continuously and
some are only checked under certain conditions.
I f the on-board diagnostic system senses t h a t one of
t h e critical circuits is bad d u r i n g a predetermined
amount of t i m e d u r i n g the m o n i t o r i n g cycle, i t w i l l
consider t h i s a real problem and puts a f a u l t code
i n t o memory. Each i n p u t a n d output c i r c u i t m o n i -
tored by the on-board diagnostic system has i t s own
fault code. T h e f a u l t code w i l l stay i n memory as
long as the c i r c u i t continues t o be bad. However, i f
the problem does n o t happen again after t h e fault
code is p u t i n t o memory, t h e engine controller is pro-
grammed t o clear the memory after 50 to 100 engine
starts.
FAULT
CODES
F a u l t
codes are t w o - d i g i t numbers
flashed
on
Check E n g i n e l a m p t h a t i d e n t i f y w h i c h circuit is
bad. I n most cases they do not identify w h i c h compo-
nent i n a c i r c u i t is bad. A f a u l t description can be
read u s i n g the D R B I I . Refer t o Group 14 - F u e l Sys-
tems for more i n f o r m a t i o n . Therefore, a f a u l t code is
only a result, not necessarily t h e reason for the prob-
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