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a. Use the multimeter in order to measure the
voltage of the starting motor, when you are
cranking or attempting to crank the engine.
b. If the voltage is equal to or greater than the
voltage that is given in table 14 , then the
battery and the starting motor cable that goes
to the starting motor are within specifications.
Go to step 6.
c. The starting motor voltage is less than the
voltage specified in table 14 . The voltage drop
between the battery and the starting motor is
too great. Go to step 5.
5. Measure the voltage.
a. Measure the voltage drops in the cranking
circuits with the multimeter. Compare the
results with the voltage drops which are
allowed in table 15 .
b. Voltage drops are equal to the voltage drops
that are given in table 15 or the voltage drops
are less than the voltage drops that are given
in table 15 . Go to step 6 in order to check the
engine.
c. The voltage drops are greater than the voltage
drops that are given in table 15 . The faulty
component should be repaired or replaced.
6. Rotate the crankshaft by hand in order to ensure
that the crankshaft is not stuck. Check the oil
viscosity and any external loads that could affect
the engine rotation.
a. If the crankshaft is stuck or difficult to turn,
repair the engine.
b. If the engine is not difficult to turn, go to step 7.
7. Attempt to crank the starting motor.
a. The starting motor cranks slowly.
Remove the starting motor for repair or
replacement.
b. The starting motor does not crank.
Check for the blocked engagement of the
pinion gear and flywheel ring gear.
Note: Blocked engagement and open solenoid
contacts will give the same electrical symptoms.
Diagnosis Procedure for 24 V 5.5 kW
Starting Motor
If the starting motor does not crank or cranks slow,
perform the following procedure:
1. Perform a visual check of the starting motor and
the circuit. Record any appropriate observations.
• Ensure that all cables and connections are
clean and tight.
• Ensure that any lead wires are not shorted.
2. Measure the voltage of the battery.
Measure the voltage across the battery posts with
the multimeter when you are cranking the engine
or attempting to crank the engine. Do not measure
the voltage across the cable post clamps.
a. If the voltage is equal to or greater than the
voltage in table 14 , then go to step 3.
b. The battery voltage is less than the voltage in
table 14 . Test the battery. Refer to Systems
Operation, Testing, and Adjusting, “Battery -
Test” for the correct procedure.
Note: Low battery voltage can be caused by the
condition of the battery or a shorted starting motor.
3. Measure the current that is sent to the T31 terminal
on the starting motor solenoid from the positive
post of the battery with a suitable ammeter. The
maximum current that flows to the T31 terminal
should be equal to 600 amp or the maximum
current that flows to the solenoid should be less
than 600 amp.
If the current is too great, a problem exists in the
starting motor. Replace the starting motor.
Note: If the following conditions exist, do not perform
the test in step 3 because the starting motor has a
problem.
• The voltage at the battery post is within 2 volts
of the lowest value in the applicable
temperature range of table 14 .
• The large starting motor cables get hot.
4. Measure the starting motor voltage from test point
(4) to test point (5) with a suitable multimeter.
a. Use the multimeter in order to measure the
voltage of the starting motor, when you are
cranking or attempting to crank the engine.
UENR0623 87
Electrical System
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