Alternator Test Procedures On Vehicle; Alternator Output Wire Resistance Test - Dodge D150 1990 Service Manual

8A - 14 BATTERY/STARTING/CHARGING SYSTEMS DIAGNOSTICS •
ALTERNATOR TEST PROCEDURES ON VEHICLE
INDEX
Page Page
How To Use Check Engine Lamp
For Fault Codes 18
Using On-Board Diagnostic System 16
Alternator Output Wire Resistance Test 14 How To Use Check Engine Lamp
Current Output Test 15 For Fault Codes 18
ALTERNATOR OUTPUT WIRE RESISTANCE TEST
(FIG. 1)
A l t e r n a t o r o u t p u t w i r e resistance test w i l l show
a m o u n t of Voltage Drop across alternator output
w i r e between a l t e r n a t o r B A T t e r m i n a l and battery
positive post.
PREPARATION
(1) Before s t a r t i n g test m a k e sure vehicle has a
f u l l y charged b a t t e r y . Test a n d procedures on how t o
check for a f u l l y charged b a t t e r y are shown i n Bat-
t e r y section o f t h i s Group.
(2) T u r n O F F i g n i t i o n switch.
(3) Disconnect b a t t e r y negative cable.
(4) Disconnect alternator o u t p u t w i r e f r o m alterna-
tor output B a t t e r y t e r m i n a l .
(5) Connect a 0-150 ampere scale D.C. ammeter i n
series between a l t e r n a t o r B A T t e r m i n a l and discon-
nected a l t e r n a t o r output w i r e . Connect Positive lead
to a l t e r n a t o r B A T t e r m i n a l a n d Negative lead to dis-
connected a l t e r n a t o r output w i r e .
(6) Connect Positive lead o f a test voltmeter (Range
0-18 volts m i n i m u m ) to disconnected alternator out-
put w i r e . Connect negative lead of test voltmeter t o
battery positive cable a t positive post.
(7) Remove a i r hose between Engine Controller and
air cleaner.
(8) Connect one end of a J u m p e r W i r e to ground
and w i t h other end probe green R3 lead w i r e at back
of a l t e r n a t o r ( F i g . 1). (This w i l l generate a f a u l t
code).
CAUTION: Do not connect blue J2 lead of wiring to
ground. Refer to Group 8W - Wiring Diagrams for
more information.
(9) Connect a n engine tachometer and connect bat-
t e r y negative cable.
(10) Connect a variable carbon pile rheostat
(C3950) between b a t t e r y t e r m i n a l s . Be sure carbon
pile i s i n " O p e n " or " O f f ' position before connecting
leads. See B a t t e r y Section, Load Testing for i n s t r u c -
tions.
TEST
(1) S t a r t engine. I m m e d i a t e l y after s t a r t i n g , reduce
engine speed t o idle.
(2) A d j u s t engine speed and carbon pile t o m a i n -
t a i n 20 amperes f l o w i n g i n circuit. Observe v o l t m e t e r
reading. V o l t m e t e r r e a d i n g should n o t exceed 0.5
volts.
RESULTS
I f a h i g h e r voltage drop i s indicated, inspect, clean
and t i g h t e n a l l connections between a l t e r n a t o r B A T
t e r m i n a l a n d b a t t e r y Positive post. A voltage drop
test m a y be performed a t each connection t o locate
connection w i t h excessive resistance. I f resistance
tested satisfactorily, reduce engine speed, t u r n off
carbon p i l e a n d t u r n off i g n i t i o n switch.
(1) Disconnect b a t t e r y negative cable.
(2) Remove test ammeter, voltmeter, carbon pile,
and tachometer.
(3) Remove " J u m p e r W i r e " .
(4) Connect a l t e r n a t o r o u t p u t w i r e t o a l t e r n a t o r
B A T t e r m i n a l post. T i g h t e n t o 5 to 6 N-m (45 t o 75
i n . lbs.).
(5) Connect b a t t e r y negative cable.
(6) Connect hose between Engine Controller a n d
a i r cleaner.
(7) U s e D R B I I to erase f a u l t code.