Check Start-Stop Switch - Guardian 4700 Repair Manual

RESULTS:
1. If battery voltage is NOT indicated in Step 1, check Wire 13
between Starter Contactor and 7.5 amp Fuse, Wire 15
between the Fuse and the Battery Charge Rectifier, and Wire
15 between the Battery Charge Rectifier and the Engine
Controller circuit 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
No. 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 frame ground by the Start-Stop
Switch.
SW1
Figure 7-16. – 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:
1. Set a VOM to its "Rx1" scale and zero the meter.
2. Inspect the ground Wire 0B, between the Start-Stop Switch
and the grounding terminal. Connect one meter test lead to
Wire No. 0B 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
frame ground. The engine should crank.
4. Remove the 7.5 amp fuse. Disconnect Wire No. 18, Wire No.
0B and Wire No. 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 7-17). Continuity should be measured. Repeat the pro-
cedure with the test lead connected to the other outer terminal.
Continuity should be measured.
18
0B
17
RESULTS:
1. If continuity is not measured in Step 2, repair, reconnect or
replace Wire 0B (between Start-Stop Switch and ground termi-
nal) as necessary.
DIAGNOSTIC TESTS
INFINITY
INFINITY
NOT ACTIVATED
INFINITY
CONTINUITY
START
CONTINUITY
INFINITY
STOP
Figure 7-17. – Test 24, Step 6
Section 7
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