Guardian Technologies 4270 manual Test 26- Test Starter Contactor, Test 27 Check Starter Motor

Section 7

DIAGNOSTIC TESTS

RESULTS:

1.If “Continuity” is not measured in Step 2, repair, reconnect or replace Wire 0 (between Start-Stop Switch and ground termi- nal) as necessary.

2.If engine cranks in Step 3 when Wire 17 is grounded, but will not crank when the Switch is set to “START”, replace the Start- Stop Switch.

3.If the Start-Stop Switch (SW1) failed any part of Steps 5 or 6, replace the switch.

4.If engine will not crank when Wire 17 is grounded, proceed as follows:

a.Use a jumper wire to connect the circuit board's Wire 17 (Pin Location 3) to ground. If engine does NOT crank, proceed to Test 25.

b.If engine cranks now, but would not crank in Step 3 of the procedure, check Wire 17 for con- tinuity between the circuit board and Start-Stop Switch. If “Continuity” is not measured, repair or replace Wire 17 between the engine control board and the Start-Stop Switch.

5.For Problem 9 (Section 6), if switch tests GOOD, go to Test 30.

TEST 25 - CHECK POWER SUPPLY TO WIRE 56

DISCUSSION:

If battery voltage is available to the Engine Controller board in Test 23, then DC voltage should be deliv- ered to Wire 56 when the Start-Stop Switch is set to “START” (Test 24). This test will check to see if the circuit board is delivering battery voltage to the Wire 56 terminal.

PROCEDURE:

1.Set a VOM to measure DC voltage (12 VDC).

2.Disconnect Wire 56 from its Starter Contactor terminal.

3.Connect the meter positive (+) test lead to Wire 56, just discon- nected. Connect the other test lead to ground. No voltage should be indicated.

4.Actuate the Start-Stop Switch to its “START” position. The meter should indicate battery voltage. If battery voltage is pre- sent, stop the procedure.

5.Connect the VOM positive (+) test lead to Wire 56 (Pin Location 7) at the Engine Controller Circuit Board. Connect the other test lead to frame ground.

6.Actuate the Start-Stop Switch to the “START” position. The meter should indicate battery voltage.

RESULTS:

1.If battery voltage was measured in Step 6, but not in Step 4, repair or replace Wire 56 between the Engine Controller Circuit

Board and Starter Contactor Relay.

2.If battery voltage was not available in Step 6, replace the Engine Controller Circuit Board.

3.If battery voltage is available in Step 4 but engine does not crank, go to Test 26.

TEST 26- TEST STARTER CONTACTOR

DISCUSSION:

If battery voltage is available to the Wire 56 circuit, but engine will not crank, one possibility of the prob- lem is a failed starter contactor.

PROCEDURE:

1.Set a VOM to measure resistance.

2.Connect one test lead to Wire 0 on the starter contactor termi- nal. Connect the other test lead to frame ground. Continuity should be measured.

3.Momentarily connect a suitable jumper cable across the two large terminal studs of the starter contactor. The engine should crank.

4.Set the VOM to measure resistance.

5.Disconnect Wire 56 and 0 from the starter contactor from termi- nals.

6.Connect one test lead to the starter contactor terminal from which Wire 56 was removed. Connect the other test lead to where Wire 0 was removed. A starter contactor coil resistance of 4.6 ohms should be measured.

RESULTS:

1.If continuity is not measured in step 1, repair or replace Wire 0 between the starter contactor and the ground terminal.

2.If engine cranks during step 3, but would not crank in test 25, remove and replace starter contactor.

3.If resistance is incorrect in step 6, replace starter contactor.

4.If starter contactor checks good, proceed to next step in flow- chart.

TEST 27 - CHECK 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.

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