(3) Usin g a voltmeter conn ected t o the bat tery
posts (see the instruction s provided by the ma nufac-
turer of th e voltmet er), mea su re the open-cir cuit volt-
age (Fig. 5).
See the Open-Circuit Voltage Table. Th is voltage
reading will in dicate the batt ery st ate-of-ch arge, but
will n ot reveal its cra nking capacity. If a bat tery ha s
an open-cir cuit voltage readin g of 12.4 volts or
grea ter, it ma y be l oa d tested to reveal its cra nking
capacity (Refer to 8 - ELECTRICAL/BATTERY SYS-
TEM/BATTERY - STANDARD PROCEDURE).
OPEN CIRCUIT VOLTAGE TABLE
Open Circuit Voltage Charge Percentage
11.7 volts or less 0%
12.0 volts 25%
12.2 volts 50%
12.4 volts 75%
12.6 volts or more 100%
STANDARD PROCEDURE - IGNITION - OFF
DRA W TEST
The term Ign ition-Off Dra w (IOD) identifies a nor-
mal con dition where power is being drained from t he
batt ery with th e ignition switch in t he Off posit ion. A
normal vehicle electrical system will draw from five
to thirty-five milliamperes (0.005 to 0.035 ampere)
with the ignit ion switch in the Off position, an d a ll
non-ignition contr olled circuits in proper workin g
order. Up to thirty-five milliam per es ar e needed to
enable th e memor y fu nctions for the P owertr ain Con -
trol Module (P CM), digit al clock, electr onica lly tu ned
radio, an d ot her modules which may va ry with th e
vehicle equipm ent.
A vehicle tha t has not been oper ated for approxi-
mately twenty da ys, may discharge th e batt ery t o an
ina dequat e level. When a vehicle will not be used for
twenty days or m ore (stored), remove the IOD fu se
from the fuseblock. Th is will reduce bat tery dischar g-
ing.
Excessive IOD can be ca used by:
• Electrical it ems left on.
• Faulty or improper ly a djusted switch es.
• Faulty or shorted elect ronic modules an d compo-
nents.
• An internally shorted generator.
• Intermittent short s in the wiring.
If th e IOD is over th irty-five milliam peres, the
pr oblem must be foun d and corrected before replac-
ing a batter y. In most cases, t he batt ery can be
charged an d returned to service after the excessive
IOD condit ion has been corrected.
(1) Verify that all electrical accessories are off.
Turn off all lamps, remove t he ignition key, and close
all door s. If the vehicle is equipped with an illumi-
nated entry system or an electr onica lly t uned r adio,
allow t he electronic timer funct ion of th ese syst ems
to automatica lly shut off (t ime out). This may t ake
up to three minutes.
(2) Deter mine th at th e underhood lamp is operat-
ing pr oper ly, th en disconn ect th e lamp wire har ness
connect or or remove the lam p bulb.
(3) Disconn ect the batt ery n egative cable.
(4) Set a n electronic digital mult i-met er t o its
highest a mperage scale. Conn ect the m ulti-meter
between t he disconn ected ba tter y negative ca ble ter-
minal clam p and th e battery negat ive ter minal post.
Make sur e th at t he doors rema in closed so tha t th e
illuminated en try system is not activa ted. The mu lti-
meter amper age reading ma y remain h igh for up t o
three m inut es, or ma y not give any r eading at a ll
while set in the highest a mperage scale, depending
upon the electr ical equipm ent in the vehicle. The
multi-m eter lea ds must be securely clamped to the
batt ery negative cable ter min al clamp and the bat -
tery negat ive term ina l post. If con tinuity bet ween t he
batt ery n egative ter minal post a nd th e negat ive cable
term inal clamp is lost during an y part of t he IOD
test, the electron ic timer funct ion will be activat ed
and all of t he tests will h ave t o be repeated.
(5) After about three minutes, the high-a mpera ge
IOD reading on the m ulti-meter should become very
low or n onexistent, depending upon th e electrical
equipm ent in the vehicle. If the ampera ge rea ding
rema ins h igh, remove an d repla ce each fuse or circu it
breaker in the Fu se Blocks, on e at a time un til the
amper age reading becomes ver y low, or nonexistent.
Refer to th e appr opr iat e wiring inform ation in th is
service manual for complete fuseblock fuse, circuit
breaker, an d circuit iden tification. This will isolate
Fig. 5 Testing Open Circuit Voltage
8F - 10 BAT T ER Y S Y S T EM VA
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