Case 580SR Service Manual page 964

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CHECKING THE STARTER MOTOR CIRCUIT
To troubleshoot the starter motor circuit rapidly and
easily, it is recommended that a battery-starter motor
testing device (quick discharge) be used, which in-
cludes a 0-20 V voltmeter and a 0-500 A ammeter to
detect problems in the starter motor circuit.
Use a testing device in accordance with the manu-
facturer's instructions. If a testing device of the type
indicated is not available, use a standard 0-20 V volt-
meter and a 0-500 A ammeter to check the operation
of the starter motor on the vehicle.
Before testing:
Z Check that the battery is properly charged.
Z Check the state of the starter motor circuit, by mak-
ing sure that no wire is cut or stripped and that the
connections are not loose.
Z Check that the motor is not seized.
Current draw of the starter motor circuit:
1. Disconnect the ground cable (negative) from the
battery (3).
2. Disconnect the positive cable from the battery on
the solenoid of the starter motor. Connect the
positive cable of the ammeter (1) to the positive
terminal of the battery and the negative cable to
the input terminal of the solenoid.
3. Reconnect the ground cable (negative) of the
battery to the negative terminal of the battery.
4. Connect the positive cable of the voltmeter (2) to
the positive terminal of the battery and the neg-
ative cable of the voltmeter to the negative termi-
nal of the battery.
5. Disconnect the injection pump fuel inlet cut-off
wire from the solenoid.
6. Start the motor and observe the values indicated
by the voltmeter and ammeter. The voltage must
remain steady at around 12 V with a current
draw of 250 to 300 A.
Z If the current draw is within the indicated range, the
starter motor (4) is operating correctly. If the voltage
reduces during the test, refer to the "Resistance of
the starter motor circuit" section below.
Z If the current draw is higher than the specified
range, check the circuit as indicated below. If tests
of the starter motor circuit have proved satisfactory,
the starter motor is defective and must be removed
in order to identify the source of the problem.
Z If the current draw is less than the specified range,
the starter motor is defective and must be removed
in order to identify the source of the problem.
SECTION 55 - ELECTRICAL SYSTEM
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