Guardian Technologies 4390, 4456 Test 50- Test Starter Motor, Shorted, open or grounded armature

SECTION 4.4

DIAGNOSTIC TESTS

PART 4

DC CONTROL

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.

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.

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

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.

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