Generac Power Systems GTH760, Service Manual

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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 manufac-
turer'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 positive 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
battery 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