Chrysler RAM TRUCK 2500 1994 Service Manual page 320

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ELECTRICAL 8A - 5
I t is now safe to install milliamp meter to check for
low amperage IOD.
(5) With test lamp still connected securely, clamp
an ammeter between battery negative terminal and
negative battery cable.
If the test lamp or the milliamp meter circuit
is broken the various timer circuits will start.
Do not open any doors or turn on any electrical
accessories with the test lamp disconnected or
the meter may be damaged.
(6) Disconnect test lamp. The current draw should
not exceed 0.020 amp. I f i t exceeds 20 milliamps iso­
late each circuit by removing circuit breakers and
fuses. The meter reading drops once the high current
problem is found. Repair this section of the circuit,
whether i t is a wiring short or component failure.
BATTERY OPEN CIRCUIT VOLTAGE TEST
A battery voltage (no load) test will show state-of-
charge of a battery that will pass the Battery Load
Test described i n this section. Before proceeding
with this test or the Battery Load Test, com­
pletely charge battery as described i n Battery
Charging in this section.
I f a battery has a no load voltage reading of 12.4
volts or greater and will not endure a load test, i t is
defective and should be replaced. Refer to Group 8B -
Battery/Starter/Generator Service for instructions. To
test battery no load voltage, perform the following
operation:
(1) Before measuring open circuit voltage, the sur­
face charge must be removed from plates. Turn head­
lamps on for 15 seconds then allow up to 5 minutes
for voltage to stabilize.
(2) Remove both battery cables, negative first. On
diesel models with dual batteries, each battery must
be disconnected and tested separately from the other.
(3) Using a voltmeter connected to the battery
posts (see instructions provided with voltmeter) mea­
sure open circuit voltage (Fig. 6).
This voltage reading will indicate state-of-charge,
but will not reveal cranking capacity. Refer to Bat­
tery Open Circuit Voltage chart.
BATTERY OPEN CIRCUIT VOLTAGE
Open Circuit Volts
Percent C h a r g e
11.7 volts o r less
0%
12.0
25%
12.2
50%
12.4
75%
12.6 o r m o r e
100%
928A-3
898A7
Fig. 6 Testing Open Circuit Voltage
BATTERY LOAD TEST
WARNING: IF BATTERY SHOWS SIGNS OF FREEZ­
ING, LEAKING, LOOSE POSTS, OR LOW ELECTRO­
LYTE LEVEL, DO NOT TEST. ACID BURNS OR
EXPLOSIVE CONDITION MAY RESULT.
A battery load test will verify cranking ability
based on the cold crank amperage rating of the bat­
tery.
Before performing battery load test, the bat­
tery must b e FULLY CHARGED.
(1) Remove both battery cables, negative first. Bat­
tery top and posts should be clean. I f test indicator is
not green, charge the battery. See Battery Charging
in this group.
(2) Connect a suitable volt-ammeter-load tester
(Fig. 7) to the battery posts (Fig. 8). Refer to operat­
ing instructions provided with the tester being used.
Check the open circuit voltage (no load) of the bat­
tery. Voltage should be equal to or greater than 12.4
volts (Fig. 7), with a green test indicator.
898A-8
Fig. 7 Volt-Amps-Load Tester—Typical
(3) Rotate the load control knob (carbon pile rheo­
stat) to apply a 300 amp load for 15 seconds then re-