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4-56.
TM5-4120-377-14
Preliminary procedure: Remove junction box cover. (See para 4-47.)
Figure 4-67. Heater Relay (K2)
a. Removal
(1) Tag and disconnect wire leads.
(2) Using wrench, remove four lock nuts from relay.
(3) Remove relay.
b. Inspection
(1) Check for loose, corroded, missing, or broken terminal connections.
(2) Check relay for cracks, evidence of overheating, and other visible damage. Replace if damaged.
c. Test
(1) Use a continuity tester or a multimeter set on the lowest OHMS scale to check continuity between
terminals A1 and A2, B1 and B2, and C1 and C2. All three contacts should be open. If there is continuity,
replace the relay.
(2) Check continuity between coil terminals X1 and X2. If there is no continuity, the coil is open. Replace
the relay.
(3) Apply external 24 volts dc power source across terminals X1 and X2 and repeat continuity checks
between terminals A1 and A2, B1 and B2, and C1 and C2. All three contacts should be closed. If there is no
continuity, replace the relay.
(4) Remove the external 24 volts dc power source from the coil terminals X1 and X2.
4-108
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