Continuity Checks - L.B. White Pilot Light Ignition Installation And Service Manual

Component
Testing

Continuity Checks

Continuity C C hecks
Equipment r r equired:
Digital Volt/Ohm Meter
Explanation:
In a continuity test, you simply want to determine whether or
not an electrical pathway exists through a component. For
these tests, it is important that the probes of the multimeter
make good contact with the part being tested. They should
touch bare metal or wire, not insulation, paint, or dirt.
Alligator clips make firmer contact than needle probes, use
them where possible.
Also, manipulate wires to see if they are loose to help
uncover loose connections.
The components which exhibit good continuity within the
electrical circuit also provide a resistance to the flow of
electricity. The resistance is measured in ohms and will be
displayed on the meter. You do not need to remove the
components to check for continuity. The following illustrates
how to check for continuity for some of the components used
in the heater.
Attention
Make sure that the heater is disconnected from its electrical
source before conducting this procedure. Failure to do so
will result in damage to your meter.
Procedure
First, set your meter to the continuity scale (if provided) or
the ohm(s) scale. Place the tester probes on the terminals
of the component being tested. If your meter has an audible
continuity feature you will hear a "ringing" sound in addition
to seeing a read out in ohms. Examples of checking for
continuity on several components are shown.
6.2-1 1
High L L imit S S witch
Typically, components which show an open circuit and are
not in proper working order will exhibit an "overload" readout
on the display of the multimeter. These components should
be replaced. However, some components such as an air
proving switch have a set of normally open contacts. To
verify proper operation, the switch arm needs to be pushed
upward or the flapper lifted so the contacts are engaged. At
this point an ohm reading should appear.
Air-P P roving S S witch
To check for proper thermostat operation, connect the
testing probe to the thermostat terminals as shown. When
the thermostat contacts are open, the meter will show an
open circuit. When the thermostat is adjusted to call for
heat, the contacts should close and you will see an ohm
readout appear on the tester indicating that there is a
completely closed electrical circuit through the thermostat.
August 1999