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Section 5. Troubleshooting
Switches (General)
Switches (General)
Examine the switch for signs of arcing,
overheating, discoloration, cracking, or other
physical damage. Replace the switch if you see
such damage.
To test a switch, isolate it from the electrical
circuit. Do this by removing all the connections
from the switch, making sure all wires are
labeled and identified for reconnection.
Use a n ohmmeter set to a low resistance scale
to measure the resistance across the switch. In
a closed position, the switch should be less
than 1 ohm. In a n open position, the switch
should show a resistance greater than 10
megohms.
5- 1 .
Figure
Hall Effect Switch Schematic
Effect Switches
The limit switches and deadman switches used
on this truck are Hall Effect switches. These
switches consist of a transistor that is turned
on when a magnet is positioned next to the
base. (Keep in mind that the magnet is part of
Toyota Orderpicker Model 7BPUE 15 Service Manual
the switch assembly and can only be seen if the
switch is disassembled.)
Figure
The switch is powered a s follows:
terminal.
Battery negative is applied to the negative
terminal.
As shown in Figure 5- 1, when a magnet is not
present, the transistor is OFF and the output
DGND
lead (Deadman
When a magnet is present, the transistor is
turned ON creating a path from the DGND
terminal to the Deadman
or active.
Key Switch
Inspection
With the battery plugged in and key switch in
the ON position, battery voltage B+ should be
present on both terminals of the switch. Test
the key switch with a n ohmmeter after
removing it from the electrical system. In the
OFF position, the ohmmeter should read
greater than 10 megohms, and in the ON
position, the ohmmeter should read less than 1
ohm. If not, replace the switch.
+
12 volts is applied to the positive
1) is in a high state.
1 terminal. Terminal
1 will now be a negative
00700-CL222-05, 1 5 March 2005
(+)
potential,
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Troubleshooting
