TM 5-5420-234-14&P
4-12. UNIT TROUBLESHOOTING (continued).
9.
LHS ENGAGED INDICATOR LIGHT DOES NOT OPERATE (MODEL A ONLY)
(continued).
NOTE
If relay K4 is defective, none of the indicator lights will work. See fault 6 - Indicator/Panel Lights Do Not
Operate.
CONTINUITY TEST
ACCESS
COVER
CAUTION
Electrical power must be shut
off from circuit before continuity
can be checked. Failure to
comply with this caution may
result in damage to test
equipment or electrical system.
CAB
UPPER
CONTROL
BODY
(1) Remove four screws and
BOX
lockwashers and access cover from
heater compartment.
(2) Remove four screws and
lockwashers from cab control box.
(3) Remove six screws from cab
control box, and separate upper
body from base.
CAUTION
Use care when removing relay
BASE
from circuit board. Failure to
comply with this caution may
result in damage to circuit board.
(4) Remove relay K4 from cab control
box circuit board.
(5) Set multimeter to ohms position.
NOTE
A reading of infinity indicates an
open circuit.
(6) Connect one multimeter lead to
side of indicator bulb socket and
the other to relay K4 socket,
position 30. Check multimeter for
continuity.
RELAY K4,
POSITION 30
Change 1
4-159
