toggles between pins 87A (when de-energized)toggles between pins 87A (when de-energized)
and 87 (when enerand 87 (when energizgized). ed). Pins 86 and 85 of thePins 86 and 85 of the
relay wilrelay will energize the coil of the relayl energize the coil of the relay. . Pin 85, inPin 85, in
all cases, is always the ground side and pin 86, inall cases, is always the ground side and pin 86, in
all casesall cases, is alway, is always the hot side. s the hot side. Either signEither signal canal can
be sent to the relay to energibe sent to the relay to energize it. ze it. EnsuEnsure that pinre that pin
85 is properly grounded, when required, and / or85 is properly grounded, when required, and / or
that 12 VDC is present at pin 86 when it isthat 12 VDC is present at pin 86 when it is
required.required.
When the relay is de-energized, the internalWhen the relay is de-energized, the internal
switch connects pins 30 and 87A completing theswitch connects pins 30 and 87A completing the
circcircuit of the two pins. uit of the two pins. When the relay iWhen the relay is ener-s ener-
gized, the coil shifts the switch, connecting pinsgized, the coil shifts the switch, connecting pins
30 and 87 completing the circuit of the two pins.30 and 87 completing the circuit of the two pins.
The most effective way to troubleshoot the relay isThe most effective way to troubleshoot the relay is
with an ohmmeterwith an ohmmeter. . This can be accomplThis can be accomplished byished by
removing the female spade connectors from pinsremoving the female spade connectors from pins
30, 87, and 87A. 30, 87, and 87A. In a In a de-ende-energiergized statzed state, ensure, ensuree
that pins 30 and 87A have continuity betweenthat pins 30 and 87A have continuity between
them. them. With an ohmmeterWith an ohmmeter, check the resis, check the resistancetance
betwbetween pins 30 and 87a. een pins 30 and 87a. The ohmmThe ohmmeter shoeter shoulduld
indiindicate a readicate a reading of 0 ng of 0 - 40 ohms. - 40 ohms. EnergEnergize theize the
relay and check the resistance between pins 30relay and check the resistance between pins 30
and 87. and 87. The ohmmThe ohmmeter should ieter should indicate a readindicate a readingng
of 0 - 40 of 0 - 40 ohmsohms. . If thesIf these two chece two checks are good, thks are good, thee
relrelay is good. ay is good. If one of these cheIf one of these checks facks fails and 12ils and 12
Normally ClosedNormally Closed
Contact (when relayContact (when relay
is de-energized)is de-energized)
Normally OpenNormally Open
Contact (when relayContact (when relay
is de-energized)is de-energized)
CommonCommon
ContactContact
IllusIllustration 6-4. tration 6-4. SPSP, ST 30 amp Relay, ST 30 amp Relay
VDC required at pin 86 was or was not present, orVDC required at pin 86 was or was not present, or
ground signal at pin 85 was or was not present,ground signal at pin 85 was or was not present,
dependant on the desired state of relay (ener-dependant on the desired state of relay (ener-
gized or de-energized), the relay is bad and mustgized or de-energized), the relay is bad and must
be replaced.be replaced.
Single-Single-Pole, Single-ThPole, Single-Throw 10 row 10 amp Relays amp Relays withwith
L.E.D.sL.E.D.s(Illustrati(Illustration on 6-5)6-5).. A relay is nothing moreA relay is nothing more
than an electricalthan an electrically controlly controlled switcled switch. h. Relays arRelays aree
always shown on electrical circuits in a de-ener-always shown on electrical circuits in a de-ener-
gized state. gized state. The positiThe positive side of the relay cve side of the relay coil isoil is
pin 14 while the negative side of the coil is pin 13.pin 14 while the negative side of the coil is pin 13.
Either signal, 12 VDC or ground (or both), can beEither signal, 12 VDC or ground (or both), can be
sent to the relay coil to energize the relay.sent to the relay coil to energize the relay.
When the relay is de-energized, the internalWhen the relay is de-energized, the internal
switch connects pins 9 and 1 completing the cir-switch connects pins 9 and 1 completing the cir-
cuit of the two picuit of the two pins. ns. When the relay iWhen the relay is energized,s energized,
the coil shifts the switch, connecting pins 9 and 5the coil shifts the switch, connecting pins 9 and 5
completing the circuit of the two pins.completing the circuit of the two pins.
When the L.E.D. is illuminated, the coil of the relayWhen the L.E.D. is illuminated, the coil of the relay
is energizis energized. ed. This does not indiThis does not indicate that the con-cate that the con-
tact points of the internal switches are functioningtact points of the internal switches are functioning
properlyproperly. . Do not rely on the L.E.DDo not rely on the L.E.D. to give the full. to give the full
operational status of the relay.operational status of the relay.
The most effective way to troubleshoot this typeThe most effective way to troubleshoot this type
relay is wirelay is with an ohmmeterth an ohmmeter. . This can be accom-This can be accom-
plished by removing the wires at relay socket ter-plished by removing the wires at relay socket ter-
minminals 9, 5, and 1. als 9, 5, and 1. In a de-enerIn a de-energizegized state, en-d state, en-
sure that terminals 9 and 1 have continuitysure that terminals 9 and 1 have continuity
between them. between them. With an ohmmWith an ohmmetereter, check the re-, check the re-
sistancsistance between termie between terminals 9 and 1. nals 9 and 1. The ohmme-The ohmme-
ter shoter should indiuld indicate a readicate a reading of 0 ng of 0 - 40 ohms. - 40 ohms. En-En-
ergize the relay and check the resistance betweenergize the relay and check the resistance between
termiterminals 9 and 5. nals 9 and 5. The ohmmeter sThe ohmmeter should indicatehould indicate
a readina reading of 0 g of 0 - 40 ohms. - 40 ohms. If thesIf these two chece two checks areks are
good, the regood, the relay is goolay is good. d. If one of these checIf one of these checksks
fails and 12 VDC required at terminal 14 was orfails and 12 VDC required at terminal 14 was or
was not present, or ground signal at terminal 13was not present, or ground signal at terminal 13
was or was not present, dependant on the desiredwas or was not present, dependant on the desired
state of relay (energized or de-energized), thestate of relay (energized or de-energized), the
relay is bad and must be replaced.relay is bad and must be replaced.
Double-Pole, Double-Throw 10 amp RelaysDouble-Pole, Double-Throw 10 amp Relays
with L.E.D.swith L.E.D.s(Illustration 6-6)(Illustration 6-6).. A relay is nothingA relay is nothing
more than an electricmore than an electrically contrally controlled switolled switch. ch. RelaysRelays
are always shown on electrical circuits in a de-en-are always shown on electrical circuits in a de-en-
ergized stergized state. ate. The positiThe positive side of the relay cve side of the relay coil isoil is
pin 14 while the negative side of the coil is pin 13.pin 14 while the negative side of the coil is pin 13.
Either signal, 12 VDC or ground (or both), can beEither signal, 12 VDC or ground (or both), can be
sent to the relay coil to energize the relay.sent to the relay coil to energize the relay.
When the relay is de-energized, the internalWhen the relay is de-energized, the internal
switch connects pins (9 and 1) and pins (12 andswitch connects pins (9 and 1) and pins (12 and
4) completing the circuit of both sets of pins.4) completing the circuit of both sets of pins.
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