Generac Power Systems GTH1000, Service Manual

Page: 38 / 74

SECTION 6: ELECTRIC STARTER
6-2
TEST STARTER MOTOR
TESTING STARTER SOLENOID:
The solenoid is a normally open, electrically activated switch. With
the keyswitch in the “START” position, the switch closes, allowing
battery current to flow to the starter motor and crank the engine.
1. The solenoid may be tested while mounted on the engine.
2. A jumper test lead is required for this test.
3. Remove positive battery cable from battery. Then remove battery
cable from stud terminal on solenoid.
4. Disconnect wire from tab terminal on solenoid.
5. Keyswitch must be in “OFF” position.
6. Insert red test lead into receptacle in meter.
7. Insert black test lead into
receptacle in meter.
8. Rotate meter selector to position.
9. Attach one meter test lead to each stud terminal on the solenoid
(Figure 6-3).
10. Attach one end of jumper lead to positive terminal on battery.
11. Touch jumper wire to tab terminal on solenoid.
a. An audible “Click” should be heard as the solenoid switch
“closes.”
b. Meter should make a continuous tone (continuity).
Figure 6-3. Testing Solenoid
CHECKING STARTER VOLTAGE DROP
Before starting this test, make sure the battery is at least 70 percent
charged (12.5 volts or higher). Also make sure the correct sized battery
is being used. Check the engine manufacturer's Operator's Manual for
battery size recommendations.
With the engine and all other accessories turned off, measure the
battery voltage across the battery posts using a VOM set to the 20
Volt scale. Do not measure across the the battery wire terminal ends.
Voltage should read 12.5 volts or higher.
Do not crank the engine longer than 15 seconds during any of the
following tests. To check starter voltage drop:
1. Prevent the engine from starting by either grounding the ignition
at the ground stud on the side of the engine or removing the spark
plug leads. Using a VOM, place the (+) positive lead on the posi-
tive post of the battery. The (-) negative lead on the negative post
on the battery. Crank the engine and observe the reading on the
VOM.
2. Next, place the (+) positive lead of the VOM on the starter’s bat-
tery terminal stud and the (-) negative lead on the starter housing.
Crank the engine and observe the VOM reading.
3. Compare the two voltage readings. If the two readings are the
same (or a difference of one volt or less) then there is no excessive
voltage drop on the positive side. If a voltage drop of greater than
one volt is seen, proceed to Step 4.
Figure 6-4. Testing Starter Voltage Drop
4. Set the VOM on the 2 volt scale. Place the (+) positive lead on
the (+) positive battery post and the (-) negative lead on the (+)
positive terminal stud on the starter. Refer to figure 6-4. With
the engine still disabled, crank the engine and observe the VOM
reading. There should be less than a 0.2 volt drop. If greater, a
check of each wire and terminal connection should be made. At
each connection, no more than 0.2 volts should be seen.