jcb 1CX, Service Manual

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5 - 1
Section C Electrics
9803/8550
Section C
5 - 1
Issue 1
Starter Motor
Starting Circuit Test
Before carrying out the voltmeter tests, check the battery
condition (see Battery Testing) and ensure that all
connections are clean and tight.
To prevent the engine starting during the tests ensure that
the engine shut off solenoid lead is disconnected at the fuel
pump.
Check the readings in the following sequence using a
voltmeter. Unless otherwise stated, the readings must be
taken with the starter switch in the 'start' position and the
transmission forward/reverse selector in neutral.
1 Connect the voltmeter across the battery terminals.
Reading in 'start' position: 10.0V approximately.
A low reading probably indicates a fault in the starter
motor.
2 Connect the voltmeter between the starter main
terminal A and the commutator end bracket B. In the
'start' position, the reading should not be more than
0.5V below the reading obtained in Test 1.
3 Connect the voltmeter between the solenoid terminal C
and a good earth.
Minimum reading in 'start' position: 8.0V.
If the reading is less than specified, connect the voltmeter
between the neutral start relay terminal D and earth. An
increase in reading to 8.0V indicates a fault in the wiring
from the start relay to the solenoid. If the reading between
terminal D and earth is below 8.0V, connect the voltmeter
between terminal E and earth. An increase in the reading to
8.0V indicates either a faulty start relay or a fault in the feed
from the transmission selector switch to the relay solenoid.
Check also the solenoid earth connection.
If the reading between E and earth is less than 8.0V, the fault
must be in either the starter switch (terminals F and G) or in
the wiring between the solenoid, starter switch, and the start
relay.
4 Connect the voltmeter between the battery negative
and starter earth connection B. The reading in the
'start' position should be practically zero.
If the reading is appreciably above zero, a high
resistance in the earth lead or connections is indicated.
5 Connect the voltmeter battery positive and the starter
main terminal A. With the starter switch 'off', the
voltmeter should indicate battery voltage, but it should
fall to practically zero when the switch is turned to the
'on' position.
If the reading is appreciably above zero, a high
resistance is present in the insulated lead or in the
solenoid. Connect the voltmeter between the battery
positive and solenoid connection H. If the voltmeter
now reads zero with the switch closed, the fault is in
the solenoid.
Finally reconnect the engine shut off solenoid lead.
S8320A
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