Guardian Technologies 4456, 4390 TEST 49- TEST STARTER CONTACTOR, Section, Part, Diagnostic Tests

DC CONTROL

PART 4

SECTION 4.4

DIAGNOSTIC TESTS

Figure 5. The Starter Contactor Relay

PROCEDURE:

1 Set a VOM to measure DC voltage.

2.Connect the positive (+) meter test lead to the Wire 13 connector. Connect the negative (-) meter test lead to a clean frame ground. Battery voltage should be measured.

3.Connect the positive (+) meter test lead to the Wire 16 connector. Connect the negative (-) meter test lead to a clean frame ground.

4.Set the AUTO-OFF-MANUAL switch to MANUAL. Observe the meter reading. Battery voltage should measured. If battery voltage is NOT measured, proceed to Step 5.

5.Set the VOM to it’s “R x 1” scale to measure ohms.

6.Connect one test lead to the Wire 0 connector. Connect the other test lead to a clean frame ground. CONTINUITY should be measured.

RESULTS:

1If battery voltage is NOT measured in Step 2, repair or replace wiring between starter contactor relay and fuse (F2).

2.If battery voltage is NOT measured in Step 4 and CONTINUITY is measured in Step 6, replace the starter contactor relay.

3.If battery voltage is measured in Step 4. proceed to Test 49.

TEST 49- TEST STARTER CONTACTOR

DISCUSSION:

The starter contactor (SC) must energize and its heavy duty contacts must close or the engine will not crank. This test will determine if the starter contactor is in working order.

PROCEDURE:

Carefully inspect the starter motor cable that runs from the battery to the starter motor. Cable connections must be clean and tight. If connections are dirty or corroded, remove the cable and clean cable terminals and terminal studs. Replace any cable that is defective or badly corroded.

Use a DC voltmeter (or a VOM) to perform this test. Test the starter contactor as follows:

1.Connect the positive (+) meter test lead to the starter contactor stud (to which the red battery cable connects). Connect the common (-) meter test lead to a clean frame

ground. Battery voltage (12 volts DC) should be indicated.

2.Now, connect the positive (+) meter test lead to the starter contactor stud to which the starter motor cable attaches (see Figure 6 or 7). Connect the common (-) test lead to frame ground.

a.No voltage should be indicated initially.

b.Set the AUTO-OFF-MANUALswitch to MANUAL. The meter should now indicate battery voltage as the starter contactor energizes.

Figure 6. The Starter Contactor (Single Cylinder Units)

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