TM-9-2320-272-23-1
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; FIELD MAINTENANCE MANUAL; VOLUME 1 OF 5
SEPTEMBER 2012
TM-9-2320-272-23-1 - Page 1224 of 1313
FIVE INDICATOR LIGHTS FLASHING - Continued
CONDITION/INDICATION
IS THERE CONTINUITY BETWEEN PRESSURE SWITCH AND CTIS WIRING HARNESS CANNON PLUG
AT ECU?
DECISION
YES - Go to Step (10).
NO - Replace CTIS wiring harness (Volume 2, WP
0322). Go to Step (17) to verify problem is solved.
STEP
10.
IS THERE CONTINUITY BETWEEN PRESSURE SWITCH PINS A AND B WHEN AIR SYSTEM IS AT
NORMAL OPERATING PRESSURE?
a.
Refer to point to point schematics.
T0422DAA
PRESSURE
TRANSDUCER
Figure 10.
Pressure Transducer.
b.
Connect multimeter red lead to to pressure switch at pin A.
c.
Connect multimeter black lead to pressure switch at pin B.
d.
Use shop air pressure or start and run engine until air pressure reaches 112-120 psi while monitoring
the instrument cluster air pressure gauge.
e.
Pressure switch should be closed.
f.
Meter reading should be less than 20 ohms.
CONDITION/INDICATION
IS THERE CONTINUITY BETWEEN PRESSURE SWITCH PINS A AND B WHEN AIR SYSTEM IS AT
NORMAL OPERATING PRESSURE?
DECISION
YES - Go to Step (11).
NO - Replace pressure switch (Volume 2, WP
0324). Go to Step (17) to verify problem is solved.
TM 9-2320-272-23-1
0146
0146-11
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