Perkins 1103D XK Systems Operation Testing And Adjusting page 46

46
Testing and Adjusting Section
Diagnosis Procedure
The procedures for diagnosing the starting motor
are intended to help the technician determine if a
starting motor needs to be replaced or repaired. The
procedures are not intended to cover all possible
faults and conditions. The procedures serve only as
a guide.
NOTICE
If equipped with electric start, do not crank the engine
for more than 30 seconds. Allow the starter to cool for
two minutes before cranking again.
Never turn the disconnect switch off while the engine
is running. Serious damage to the electrical system
can result.
If the starting motor does not crank or cranks slow,
perform the following procedure:
1. Use a suitable digital multimeter in order to
measure the voltage of the battery.
Measure the voltage across the battery posts
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 or greater than the
voltage in Table 15, then go to Step 2.
b. The battery voltage is less than the voltage in
Table 15.
A low charge in a battery can be caused by
several conditions.
•
Deterioration of the battery
•
A shorted starting motor
•
A faulty alternator
•
Loose drive belts
•
Current leakage in another part of the
electrical system
The correct procedures to test the battery can
be found in the manual that is supplied by the
OEM.
2. Use a suitable ammeter in order to measure the
current that is sent to the starting motor solenoid
from the positive post of the battery.
Note: If the following conditions exist, do not perform
the test in Step 2 because the starting motor has a
fault.
This document has been printed from SPI². Not for Resale
•
The voltage at the battery post is within 2 volts
of the lowest value in the applicable temperature
range of Table 15.
•
The large starting motor cables get hot.
Place the jaws of the ammeter around the cable
that is connected to the "bat" terminal. Refer to
Specifications, "Starting Motor" for the maximum
current that is allowed for no load conditions.
The current and the voltages that are specified
in Specifications are measured at a temperature
of 27°C (80°F). When the temperature is below
27°C (80°F), the voltage will be lower through the
starting motor. When the temperature is below
27°C (80°F), the current through the starting motor
will be higher. If the current is too great, a fault
exists in the starting motor. Repair the fault or
replace the starting motor.
If the current is within the specification, proceed
to Step 3.
3. Use a suitable digital multimeter in order to
measure the voltage of the starting motor, when
you are cranking or attempting to start the engine.
a. If the voltage is equal or greater than the
voltage that is given in Table 15, then the
battery and the starting motor cable that goes
to the starting motor are within specifications.
Go to Step 5.
b. The starting motor voltage is less than the
voltage specified in Table 15. The voltage drop
between the battery and the starting motor is
too great. Go to Step 4.
4. Use a suitable digital multimeter in order to
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 16.
b. Voltage drops are equal to the voltage drops
that are given in Table 16 or the voltage drops
are less than the voltage drops that are given
in Table 16. Go to Step 5 in order to check the
engine.
c. The voltage drops are greater than the voltage
drops that are given in Table 16. The faulty
component should be repaired or replaced.
5. 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.
KENR6912