Most of the testing of the electrical system can be done
on the engine. The wiring insulation must be in good
condition, the wire and cable connections clean and tight
and the battery fully charged. If on the engine test shows
a defect in a component, remove the component for
5P300 Electrical Tester.
9S1990 or 1P7400 Battery Charger Tester.
5P957 or 5P3414 Coolant and Battery Tester.
The battery circuit is an electrical load on the charging
unit. The load is variable because of the condition of
the charge in the battery. Damage to the charging unit
will result, if the connections, (either positive or
negative) between the battery and charging unit are
broken while the charging unit is charging. This is
because the battery load is lost and there is an increase
in charging voltage.
High voltage will damage, not only the charging unit but
also the regulator and other electrical components.
9S1990 BATTERY CHARGER TESTER
Never disconnect any charging unit
circuit or battery circuit cable from
battery when the charging unit is
Load test a battery that does not hold a charge when in
use. To do this, put a resistance, across the battery
main connections (terminals). For a 6 volt battery, put a
resistance of two times the ampere/ hour rating of the
battery. For a 12 volt battery, put a resistance of three
times the ampere/ hour rating. Let the resistance
remove the charge (discharge the battery) for 15
seconds. Immediately test the battery voltage. A 6 volt
battery in good condition will test 4.5 volts; a 12 volt
battery in good condition will test 9 volts.
5P300 Electrical Tester.
The condition of charge in the battery at each regular
inspection will show if the charging system is operating
correctly. An adjustment is necessary when the battery
is always in a low condition of charge or a large amount
of water is needed (one ounce per cell per week or
every 50 service hours).
Test the charging units and voltage regulators on the
engine, when possible, using wiring and components
that are a permanent part of the system. Off the engine
(bench) testing will give an operational test of the
charging unit and voltage regulator. This testing will
give an indication of needed repair. Final testing will
give proof that the units are repaired to their original
Before starting on the engine testing, the charging
system and battery must be checked. See the following
Battery must be at least 75% (1.240 Sp. Gr.)
full charged and held tightly in place. The
battery holder must not put too much stress on
Cables between the battery, starter and engine
ground must be the correct size. Wires and
cables must be free of corrosion and have cable
support clamps to prevent stress on battery
instruments that have direct relation to the
charging circuit must give proper circuit control.
Inspect the drive components for the charging
unit to be sure they are free of grease and oil
and are able to drive the load of the charging
Alternator Regulator (Delco-Remy)
The voltage adjustment screw for the alternator is
located under the end plate.
To adjust the voltage setting, use the following