Guardian 4389 Repair Manual page 104

SECTION 4.4
DIAGNOSTIC TESTS
PROCEDURE:
The battery should have been checked prior to this
test and should be fully charged.
Set a VOM to measure DC voltage (12 VDC).
Connect the meter positive (+) test lead to the starter
contactor stud which has the small jumper wire con-
nected to the starter. Connect the common (-) test
lead to the starter motor frame.
Set the START-STOP Switch to its "START" position and
observe the meter. Meter should Indicate battery voltage,
starter motor should operate and engine should crank.
RESULTS:
1. If battery voltage is indicated on the meter but starter
motor did NOT operate, remove and bench test the
starter motor (see following test).
2. If battery voltage was indicated and the starter motor tried
to engage (pinion engaged), but engine did NOT crank,
check for mechanical binding of the engine or rotor.
If engine turns over slightly, go to Test 62 "Check and
Adjust Valves." Compression release on single cylin-
der engines may not be working, or mechanical bind-
ing is occurring.
Figure 8. Starter Motor (V-Twin Engines)
Figure 9. Starter Motor (Single Cylinder Engines)
Page 102
PART 4
CHECKING THE PINION:
When the starter motor is activated, the pinion gear
should move and engage the flywheel ring gear. If the
pinion does not move normally, inspect the pinion for
binding or sticking.
Figure 10. Check Pinion Gear Operation (V-Twin)
Figure 11. Check Pinion Gear Operation
(Single Cylinder)
TOOLS FOR STARTER PERFORMANCE TEST:
The following equipment may be used to complete a
performance test of the starter motor:
• A clamp-on ammeter.
• A tachometer capable of reading up to 10,000 rpm.
• A fully charged 12-volt battery.
MEASURING CURRENT:
To read the current flow, in AMPERES, a clamp-on
ammeter may be used. This type of meter indicates
current flow through a conductor by measuring the
strength of the magnetic field around that conductor.
DC CONTROL
PINION
PINION