Daewoo G424 Gasoline Service Manual page 35

The result of these switches and relays is to permit a
5 amp dash-mounted switch to turn on a 500 to 1000
amp motor used to crank an engine.
Battery voltage (power) available during cranking
varies according to the temperature of the batteries.
The following chart is a guide as to what to expect
from a normal system.
TYPICAL SYSTEM VOLTAGE DURING CRANKING
AT VARIOUS AMBIENT TEMPERATURES
Temperature
-23 to -7 C (-10 to 20 F)
-7 to 10 C (20 to 50 F)
10 to 27 C (50 to 80 F)
Figure 1
The next chart shows maximum acceptable voltage
loss in the high current battery circuit feeding the
starting motor. These values are maximums for
machines of approximately 2000 SMH and up. Newer
machines would be less than those shown.
MAXIMUM ACCEPTABLE SYSTEM VOLTAGE
DROPS DURING CRANKING
Circuit
Battery(-) post to starting motor
(-) terminal
Battery (+) post to solenoid (+) terminal
Solenoid Bat terminal to
solenoid Mtr terminal
Figure 2
Voltages greater than those shown are most often
caused by loose and/or corroded connections or
defective switch contacts.
Diagnosis Procedure
TOOLS NEEDED
Digital Multimeter or Equivalent
DC Clamp-On Ammeter or Equivalent
NOTICE
Do not operate the starting motor for more than 30
seconds at a time. After 30 seconds, the cranking
must be stopped for two minutes to allow the starting
motor to cool. This will prevent damage to the starting
motor due to excessive heat buildup.
G424 Service Manual
12V System
6 to 8 Volts
7 to 9 Volts
8 to 10 Volts
12V System
0.7 Volts
0.5 Volts
0.4 Volts
1
1
34
If the starting motor cranks real slow or does not crank
at all, do the following procedure:
1. Measure battery voltage at the battery posts with
the multimeter while cranking or attempting to crank
the engine. Make sure to measure the battery
posts. Do not measure the cable post clamps.
2. Is battery voltage equal to or greater than shown in
Figure 1?
I
If the battery voltage is correct, go to Step 3.
I
If the battery voltage is too low, Charge or replace
the battery.
NOTE: A low battery can be caused by battery
condition or a shorted starting motor.
3. Measure current draw on the (+) battery cable
between the battery and the starting motor solenoid
with the clamp-on ammeter. The maximum current
draw allowed is 350 Amp. At temperatures below
27°C (80°F), the voltage will be less and the current
draw will be higer. If current draw is too much, the
starting motor has a problem and must be removed
for repair or replacement.
NOTE: If voltage at the battery post is within
approximately 2 volts of the lowest value in the
applicable temperature range of Figure1 and if the
large starting motor cables get hot, then the starting
motor has a problem and the Ammeter test is not
needed.
4. Measure starting motor voltage from test point (4) to
(5) with the multimeter while cranking or attempting
to crank the engine.
5. Is voltage equal to or greater than shown in Figure
1?
I
If the starting motor voltage is correct, the battery
and starting motor cables down to the motor are
within specifications. Go to Step 8.
I
If the starting motor voltage is low, the voltage drop
between the battery and the starting motor is too
great. Go to Step 6.
6. Measure the voltage drops in the cranking circuits
with the multimeter. Compare the results with
maximum voltage drops allowed in Figure 2.
Starting System