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Testing the voltage drop in earth line
Test equipment
0 to 20 V dc voltmeter
NOTE :
This test can be made with the starter motor
still installed on the machine.
Do the voltage drop in earth line test as follows:
1. Open the hood.
2. Connect the voltmeter between the battery earth
terminal and the starter earth (commutator end
bracket).
3. When the starter switch is closed the voltmeter
should read practically zero.
4. If reading is high, clean and tighten all earth con-
nections and check bonding strap.
5. Close the hood.
789M056A
Testing the no-load current and speed
Test equipment
Test bench
Mechanical tachometer 0 to 10,000 rpm
Ammeter up to 150 A capacity
Do the no-load current and speed test as follows:
1. If necessary, remove the starter motor from the
machine.
2. Connect an ammeter in circuit between the
starter solenoid and battery.
3. Hold the tachometer against the end of the pin-
ion shaft and operate the starter switch.
4. Max. current: 115 A at 11 V.
Max. speed: 5500 to 8000 rpm.
Excess current indicates that starter is faulty.
5. If low current is registered, do the continuity of
contacts test.
6. If starter fails to operate and there is no audible
operation of solenoid, then connect the ammeter
across the “STA” terminal and the battery.
Key
A STARTER SWITCH
B TACHOMETER POSITION
789M057A
7. Operate the starter switch, the starter motor
should run, indicating a faulty solenoid which
must be replaced.
8. If the starter motor does not run, the motor itself
is faulty.
9. If the starter motor fails to operate but the sole-
noid operation is audible, do the continuity of
contacts test.
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