Guardian Technologies 4758 User Manual
Page 103
SECTION 4.4
DIAGNOSTIC TESTS
PART 4
Figure 7. The Starter Contactor (V-twin Units)
RESULTS:
1. If battery voltage was indicated in Step 1, but NOT in
Step 2b, replace the starter contactor.
2. If battery voltage was indicated in Step 2b, but the
engine did NOT crank, go on to Test 50.
TEST 50- TEST STARTER MOTOR
CONDITIONS AFFECTING STARTER MOTOR
PERFORMANCE:
1. A binding or seizing condition in the starter motor bearings.
2. A shorted, open or grounded armature.
a. Shorted, armature (wire insulation worn and
wires touching one another). Will be indicated
by low or no RPM.
b. Open armature (wire broken) will be indicated
by low or no RPM and excessive current draw.
c. Grounded armature (wire insulation worn and wire
touching armature lamination or shaft). Will be
indicated by excessive current draw or no RPM.
3. A defective starter motor switch.
4. Broken, damaged or weak magnets.
5. Starter drive dirty or binding.
DISCUSSION:
Test 47 verified that circuit board action is delivering
DC voltage to the starter contactor relay (SCR). Test
48 verified the operation of the SCR. Test 49 verified
the operation of the starter contactor (SC). Another
possible cause of an "engine won’t crank" problem is
a failure of the starter motor.
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
connected 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
cylinder engines may not be working, or mechanical
binding is occurring.
Figure 8. Starter Motor (V-Twin Engines)
Figure 9. Starter Motor (Single Cylinder Engines)
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.
DC CONTROL
Page 4.4-6