215204 Rev. 1 23
ROUBLESHOOTING
T
4.5 Electrical Circuit
(Solenoid-equipped Clamps)
Use the electrical schematic and diagram shown and
follow the steps below:
1 Check the control knob circuit fuse. Replace if
necessary.
2 Check for loose electrical connections at the truck
ignition switch, control knob button, solenoid coil
terminals and diode.
3 Remove the diode from the solenoid coil terminal. Test
with an ohmmeter for high resistance in one direction
and no resistance in the other direction. If there is no
resistance in both directions, replace the diode.
NOTE: When replacing the diode, the banded (+) end
must be connected to the coil and wiring as shown.
4 Disconnect the electrical leads from the solenoid coil
terminals. Use a voltmeter to determine if voltage is
present at the electrical leads when the button is
depressed.
• If there is no current to the solenoid, troubleshoot
the electrical circuit for shorts.
• If there is current to the solenoid, test for coil
continuity.
5 Test for coil continuity by placing an ohmmeter test
lead on each solenoid coil terminal (ohmmeter on Rx1
scale).
• If there is an ohmmeter reading, the coil is good.
• If the coil is good, but the solenoid does not 'click'
when the control knob button is depressed, the
solenoid cartridge may be jammed. Refer to
Section 5.6.
• If there is no ohmmeter reading, the coil is defective
and should be replaced. Refer to Section 5.6.
Solenoid Coil
CL0258.ill
CL0257.ill
Solenoid Coil
User-supplied wire
7.5-Amp
Fuse
White
Black
7.5-Amp Fuse
White Black
Solenoid Coil
Diode
Diode
Knob
Button
Control Lever Knob
with Pushbutton
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