SECTION 8 - GENERAL ELECTRICAL INFORMATION & SCHEMATICS
8
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Continuity Measurement Over Long Distances
When trying to determine continuity of a harness or
wire, longer than the reach of standard instrument
leads, is possible to perform the check without exces-
sively long leads. Using the other wires in the harness
one can determine the condition of a particular wire in
the harness.
Requirements:
•
Harness with at least three separate wires including
the wire under test.
•
These wires must be able to be isolated from other
wires, etc.
•
Jumper or method to connect contacts on one side of
harness.
•
Meter that can measure resistance or continuity.
Procedure
Test multimeter leads resistance. Subtract this value
from the measured resistance of the wires to get a more
accurate measurement. Consult the circuit schematic to
determine which wires to use in addition to wire under
test, here called wire #1 and wire #2, and how to isolate
these wires. These wires should appear in the same con-
nectors as the wire under test or are within reach of the
jumper.
1.
Disconnect all connections associated with the
wire under test and the two additional wires. If
harness is not completely isolated disconnect
battery terminals also, as a precaution.
2.
Measure continuity between all three wires, the
wire under test, wire #1 and wire #2. These
should be open. If not, repair the shorted wires
or replace the harness.
3.
On one side, jumper from contact of wire #1 and
wire #2.
4.
Measure continuity between wire #1 and wire
#2. If there is continuity, both wires are good and
can be used for this test. If there is not continuity,
either wire could be bad. Check connections and
measurement setup. Redo measurement. If still
no continuity, repair wires or consult schematic
for other wires to use for test.
5.
Jumper from wire under test to wire #1.
6.
Measure continuity. If there is continuity, the
wire under test is good. Resistance of a wire
increases as the length increases and as the
diameter decreases.
One can find the continuity of two wires, here #1 and #2,
at once by following steps 1 through 4. If there is a prob-
lem the third wire is used to troubleshoot the other
wires. To find the problem, start at step 1 and use the
entire procedure.
8.3
APPLYING SILICONE DIELECTRIC COMPOUND TO
AMP CONNECTORS
Silicone Dielectric Compound must be used on the AMP
connections for the following reasons:
•
To prevent oxidation at the mechanical joint between
male and female pins.
•
To prevent electrical malfunction caused by low level
conductivity between pins when wet.
Use the following procedure to apply Silicone Dielectric
Compound to the electrical connectors.
1.
To prevent oxidation and low level conductivity,
silicone dielectric grease must be packed com-
pletely around male and female pins on the
inside of the connector after the mating of the
housing to the header. This is easily achieved by
using a syringe to fill the header with silicone
dielectric compound, to a point just above the
top of the male pins inside the header. When
assembling the housing to the header, it is possi-
ble that the housing will become air locked, thus
preventing the housing latch from engaging.
2.
Pierce one of the unused wire seals to allow the
trapped air inside the housing to escape.
3.
Install a hole plug into this and/or any unused
wire seal that has silicone dielectric compound
escaping from it.
8.4
INSTALLATION OF DIELECTRIC GREASE
The following is general guidance for the installation of
dielectric grease in a connector system.
•
Use dielectric grease in a tube for larger connection
points or apply with a syringe for small connectors.
•
Apply dielectric grease to plug/male connector hous-
ing which typically contains sockets contact/female
terminals.
•
Leave a layer of dielectric grease on the mating face of
the connector, completely covering each connector
terminal hole. Refer the pictures shown below.
•
Assemble the connector system immediately to pre-
vent moisture ingress or dust contamination.
The following connector systems are specifically
addressed because of their widespread use at JLG. How-
ever, this guidance may be applied to similar devices.
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