ENGINE DIVISION SERVICE MANUAL
ELECTRICAL
Fig. 7. Cranking Circuit Test
1. Voltmeter
Values of maximum voltage drops for a standard 12-
volt cranking circuit are as follows:
Volt
Cable Under Three (3) Feet
.1
Cable Over Three (3) to
Six (6) Feet
.2
Mechanical Switch
.1
Solenoid Switch
.2
Magnetic Switch
.3
Each Connection
.0
Add these values together. For ex-ample, you have
a total of .5 volt and you have less than .5 volt drop,
continue to grounded side test.
However, if you have more than .5 volt drop, you
have an excessive voltage drop. This must be located
by moving test lead from starting motor and working
toward the battery. Crank engine and each move.
When a noticeable decrease in the voltage reading is
obtained, the trouble will be located between that point
and the preceding point checked.
Items which could be at fault can either be a
damaged cable or poor connection, an undersized wire
or possibly a bad solenoid (contact within the solenoid).
Repair the fault.
Grounded Size:
High resistance in ground circuit
of starting motor system will result in hard starting and
may affect the charging circuit as well.
Connect voltmeter leads to ground on starting motor
and to ground post of battery. The allowable voltage
drop of .2 volt is permissible. If more than .2 volt is
obtained, a poor ground is pre-sent, such as a loose
starting motor mounting bolt, bad battery ground
connector or ground connection to engine or frame,
depending upon the battery installation. The excessive
voltage drop is located in much the same manner as in
the preceding test working toward the battery.
CGES-230 - Page 8
PRINTED IN UNITED STATES OF AMERICA
