To test the switch, touch the test light to the switch
output wire connection while moving the shift lever.
The light should glow as the shift lever is slid into park
or neutral. The light should not work in any other
position. If the light is not working properly, check the
mechanism that operates the switch. If the problem is
in the switch, replace it.
Starter Current Draw Test
STARTING CIRCUIT MAINTENANCE
The condition of the starting motor should be
carefully checked at each PM service. This permits you
to take appropriate action, where needed, so equipment
failures caused by a faulty starter can be reduced, if not
The starter current draw test measures the amount
of amperage used by the starting circuit. It quickly tells
you about the condition of the starting motor and other
circuit components. If the current draw is lower or
higher than the manufacturers specifications, there is a
problem in the circuit.
A visual inspection for clean, tight electrical
connections and secure mounting at the flywheel
housing is the extent of the maintenance check. Then
operate the starter and observe the speed of rotation
and the steadiness of operation. To prevent the starter
from overheating, do NOT operate the starter for more
than 30 seconds.
To perform a starter current draw test, you may use
either a voltmeter or inductive ammeter or a battery
load tester. These meters are connected to the battery to
measure battery voltage and current flow out of the
battery. For setup procedures, use the manufacturers
manual for the type of meter you intend to use.
If the starter is not operating properly, remove the
starter, disassemble it, and check the commutator and
brushes. If the commutator is dirty, it may be cleaned
with a piece of No. 00 sandpaper. However, if the
commutator is rough, pitted, or out-of-round or if the
insulation between the commutator bars is high, it
must be reconditioned using an armature lathe.
To keep a gasoline engine from starting during
testing, disconnect the coil supply wire or ground the
coil wire. With a diesel engine, disable the fuel
injection system or unhook the fuel shutoff solenoid.
Check the manufacturers service manual for details.
With the engine ready for testing, crank the engine
and note the voltage and current readings. Check the
manufacturers service manual. If they are not within
specifications, there is something wrong with the
Brushes should be at least half of their original
size. If not, replace them. The brushes should have free
movement in the brush holders and make good, clean
contact with the commutator.
Once the starter is checked and repaired as needed,
it should be reassembled, making sure that the starter
brushes are seated. Align the housings and install the
bolts securely. Install the starter in the opening in the
flywheel housing and tighten the attaching bolts to the
specified torque. Connect the cable and wire lead
firmly to clean terminals.
STARTING MOTOR CIRCUIT TESTS
There are many ways of testing a starting motor
circuit to determine its operating condition. The most
common tests are as follows:
The starter current draw test is used to measure
the amount of amperage used by the starting
The starter circuit voltage drop tests (insulated
circuit resistance test and starter ground test) are
used to locate parts with higher than normal
Do NOT crank the engine for more than 30
seconds or starter damage can result. If the
starter is cranked too long, it will overheat.
Allow the starter to cool for a few minutes if
more cranking time is needed.
Starting Circuit Voltage Drop Tests
A voltage drop test will quickly locate a
component with higher than normal resistance. This
test provides an easy way of checking circuit
condition. You do NOT have to disconnect any wires
and components to check for voltage drops. The two
types of voltage drop tests are the insulated circuit
resistance test and the starter ground circuit test.
INSULATED CIRCUIT RESISTANCE
TEST.The insulated circuit resistance test checks
ail components between the positive terminal of the
battery and the starting motor for excess resistance.