ENGINE DIVISION SERVICE MANUAL
ELECTRICAL
Fig. 8. Control Circuit Test
Control Circuit: High resistance in the control circuit
will reduce the cur-rent flow through the solenoid
windings, which can cause improper function of solenoid
or not at all. Improper functioning of the solenoid could
result in burning of contacts in the solenoid causing high
resistance in the starting motor circuit.
To complete control circuit test, check the vehicle circuit
diagram to assist in locating the wires and particular
switches involved in the chassis. Observe polarity of
voltmeter and connect leads to battery post and solenoid
switch terminal as shown in Fig. 8. Crank engine using
the vehicle ignition switch or push button if equipped,
observing the voltmeter reading. If the voltmeter shows
less than .5 volt, the circuit is in good condition. If more
than .5 volt, this is an indication of excessive resistance.
Note: Occasionally a slightly higher voltage will
be found in the circuit and the circuit still be normal.
Isolate the point of high resistance by placing the
voltmeter leads across each component in the circuit in
turn. A reading of more than .1 volt across any one wire
or switch is usually an indication of the trouble.
After completing the cranking volt-age test, battery
capacity test and the voltage drop tests, and the starting
motor still fails to function, remove the motor and make
the no load test as follows.
Note that the preceding tests were made in the
particular order to make certain the starting motor circuit
is in good condition before needless starter motor
removal.
CGES-230 - Page 9
PRINTED IN UNITED STATES OF AMERICA
