Test 24 Check START-STOP Switch | Guardian Technologies 4270

Section 7

DIAGNOSTIC TESTS

3.Set the VOM to measure resistance (“Rx1” scale). Connect one meter test lead to Wire 0, Terminal 2 on the Engine Controller Circuit Board. Connect the other test lead to a clean frame ground. “Continuity” should be measured.

RESULTS:

1.If battery voltage is NOT indicated in Step 1, check continuity of:

a.Wire 13 between Starter Contactor and Preheat Contactor.

b.Wire 13 between Preheat Contactor and 14 Amp Fuse (F1).

c.Wire 15 between the 14 Amp fuse (F1) and the Battery Charge Rectifier.

d.Wire 15 between the Battery Charge Rectifier and the Engine Controller Board.

Repair, reconnect or Replace bad wiring as necessary.

2.If battery voltage is indicated but engine will not crank, go to Test 24.

3.If “Continuity” was not measured in Step 3, repair or replace Wire 0 between the Engine Controller Circuit Board and the Ground Terminal.

TEST 24 - CHECK START-STOP SWITCH

DISCUSSION:

Engine cranking and startup is initiated when Wire 17 from the Engine Controller board is connected to frame ground by setting the Start-Stop Switch to “START”.

Engine shutdown occurs when circuit board Wire 18 is connected to ground by the Start-Stop Switch.

SW117

Figure 7-12. – Start-Stop Switch

A defective Start-Stop Switch can result in (a) failure to crank when the switch is set to “START”, and/or (b) failure to shut down when the switch is set to “STOP”.

PROCEDURE:

For Problem 6 (Section 6), perform all steps. For Problem 9, perform Step 1 and Step 5 ONLY.

1.Set a VOM to its “Rx1” scale and zero the meter.

2.Inspect the ground Wire 0, between the Start-Stop Switch and the grounding terminal. Connect one meter test lead to Wire 0 on SW1. Connect the other test lead to a clean frame ground. “Continuity” should be measured.

3.Disconnect Wire 17 from its Switch terminal and connect it to ground. The engine should crank.

4.Remove the 14 amp fuse. Disconnect Wire 18, Wire 0 and Wire 17 from the Start-Stop Switch (SW1).

5.Connect one test lead to the center terminal of SW1. Connect the other test lead to an outer terminal of SW1. “Infinity” should be measured. Remove the test lead from the outer terminal of SW1 and connect it to the opposite outer terminal. “Infinity” should be measured.

6.Leave the test lead connected to the center terminal of SW1 from Step 5. Connect the other test lead to an outer terminal. Depress the switch away from the terminal being tested (see Figure 7-13). “Continuity” should be measured. Repeat the pro- cedure with the test lead connected to the other outer terminal. “Continuity” should be measured.

INFINITY

NOT ACTIVATED

INFINITY

DEPRESSED

AWAY FROM

INFINITYTERMINAL BEING TESTED

CONTINUITY

DEPRESSED

INFINITYAWAY FROM TERMINAL BEING TESTED

Figure 7-13. – Test 24, Step 6

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