TM 5-3805-262-20
INSPECTION , TESTING, AND REPAIR (SHEET 3 OF 5)
(5)
( 6)
(a)
(b)
(c)
(d)
( e)
(7)
( a)
(b)
( c )
(d)
( e)
Inspect resistor (8) for cracks, breaks, and discoloration due to over-
heating. Connect multimeter between ends of resistor. Multimeter should
indicate 36 to 44 ohms. Replace resistor if any of the above conditions
are observed or if proper multimeter indication is not obtained.
Inspect air pressure switch (12) for cracks, breaks, damaged threads,
distortion, broken or missing terminals, or other damage. Replace switch
if any of these conditions are seen. Test air pressure switch as follows:
Connect air pressure switch to a source of compressed air and pressure
r e g u l a t o r.
Connect multimeter between air pressure switch terminals.
Increase air pressure applied to air pressure switch to 90 psi, then
slowly decrease pressure while watching pressure regulator gage and mul-
timeter. Multimeter should indicate no continuity (open circuit) above
76 psi. When pressure reaches 76 to 64 psi, multimeter should indicate
continuity. Multimeter should continue to indicate continuity as
pressure decreases to zero psi.
Disconnect multimeter and remove air pressure switch from compressed air
s o u r c e.
Replace air pressure
are not obtained.
Inspect parking brake
d i s t o r t i o n , b r o k e n or
switch if multimeter indications in step (c) above
switch (15) for cracks, breaks, damaged threads,
missing terminal, or other damage. Replace switch
if any of these conditions are seen. Test parking brake switch as fol-
lows :
Connect parking brake switch to a source of compressed air and pressure
r e g u l a t o r .
Connect multimeter between air pressure switch terminal and clean metal
area of body.
Increase air pressure applied to air pressure switch to 20 psi, then
slowly decrease pressure while watching pressure regulator gage and mul-
timeter. Multimeter should indicate no continuity (open circuit) above
15 psi. When pressure reaches
10 to 14 psi, multimeter should indicate
continuity. Multimeter should continue to indicate continuity as
pressure decreases to zero psi.
Disconnect multimeter and remove parking brake switch from compressed
a i r s o u r c e.
Replace parking brake switch if multimeter indications in step (c) above
are not obtained.
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