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 939 of 1313
LOW AIR PRESSURE WARNING BUZZER WILL NOT SHUT OFF AND PARKING BRAKE WARNING LIGHT
FLASHES WITH HAND/PARKING BRAKE IN ANY POSITION (AIR PRESSURE NORMAL) - Continued
STEP
1.
IS PARKING BRAKE PRESSURE SWITCH WORKING PROPERLY?
a.
Check continuity for parking brake pressure switch.
b.
Release parking brake.
PARKING BRAKE VALVE
T1005DAA
PARKING BRAKE SWITCH
Figure 1.
Pressure Switch.
c.
Disconnect wires 584 from parking brake pressure switch (under cab).
d.
Set up multimeter to measure resistance.
e.
Connect multimeter red lead to contact end of pressure switch. Refer to point to point schematics.
f.
Connect multimeter black lead to good ground.
g.
Meter reading should be less than 200 ohms.
CONDITION/INDICATION
IS PARKING BRAKE SWITCH WORKING PROPERLY?
DECISION
NO - Replace parking brake switch (Volume 3, WP
0431). Go to Step (3) to verify problem is solved.
YES - Go to Step (2).
STEP
2.
IS WIRE 584 IN GOOD CONDITION?
a.
Install wire 584 to parking brake pressure switch.
TM 9-2320-272-23-1
0111
0111-2
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