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 1162 of 1313
FRONT WHEEL DRIVE DOES NOT ENGAGE (FRONT WHEEL DRIVE LOCK-IN SWITCH ENGAGED AND
TRANSFER CASE SHIFT LEVER IN HIGH POSITION) - Continued
STEP
6.
IS THERE AIR PRESSURE IN THE AIR LINE BETWEEN THE ACTUATOR VALVE AND THE FRONT WHEEL
DRIVE LOCK-IN SWITCH?
a.
Disconnect air line from actuator valve. Refer to point to point schematics.
T0320DAA
AIR LINE
(TO FRONT WHEEL DRIVE
LOCK - IN SWITCH)
ACTUATOR VALVE
DELIVERY LINE
SUPPLY LINE
TRANSDUCER
Figure 6.
Air Supply Line to Actuator Valve.
b.
Connect pressure gauge to disconnected air line.
c.
Start engine and run at idle.
d.
Place transfer case shift lever into high position.
e.
Engage front wheel drive lock-in switch.
f.
Monitor air pressure on pressure gauge.
g.
After 5 minutes air pressure should read 90 to 130 psi.
CONDITION/INDICATION
IS THERE AIR PRESSURE IN THE AIR LINE BETWEEN THE ACTUATOR VALVE AND THE FRONT WHEEL
DRIVE LOCK-IN SWITCH?
DECISION
YES - Notify supervisor. Action may not be possible at this level of maintenance.
NO - Go to Step (7).
TM 9-2320-272-23-1
0140
0140-7
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