
October 2008
Section 4 • Repair Procedures
4 - 60
GS-30 • GS-32 • GS-46
Part No. 96316
REV B
4-2
Control Relays
Relays used for single function switching are single
pole double throw (SPDT) relays.
How to Test a Single Pole Double
Throw Relay
Electrocution/burn hazard. Contact
with electrically charged circuits
could result in death or serious
injury. Remove all rings, watches
and other jewelry.
1 Label and then disconnect all the wiring from
the relay to be tested.
2 Connect the leads from an ohmmeter or
continuity tester to each terminal combination
and check for continuity. Terminals 85 and 86
represent the coil and should not be tested in
any other combination.
Test
Desired result
terminal 85 to 86 with resistor
310 to 330
Ω
terminal 87 to 87a and 30
no continuity
(infinite
Ω)
terminal 87a to 30
continuity
(zero
Ω
)
3 Connect 24V DC and a ground wire to terminals
85 and 86, then test the following terminal
combinations.
Test
Desired result
terminal 87a to 87 and 30
no continuity
(infinite
Ω)
terminal 87 to 30
continuity
(zero
Ω
)
GROUND CONTROLS
Relay schematic - deactivated
85
87
86
87a
30
30
87a
87
86
85
30
87a
87
86
85
Relay schematic - activated
Terminal Number Legend
terminal no. 87a - N.C.
terminal no. 85 - ground
terminal no. 30 - common
terminal no. 86 - coil
terminal no. 87 - N.O.