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 1158 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
2.
DOES AIR SYSTEM LEAK WITH SHIFT LEVER IN HIGH POSITION?
a.
Place transfer case shift lever into high position. Refer to point to point schematics.
T0340DAA
TRANSFER
CASE SHIFT
LEVER
FRONT WHEEL
DRIVE LOCK - IN
SWITCH
Figure 2.
Transfer Case Shift Lever and Drive Lock In Switch.
b.
Engage front wheel drive lock-in switch.
c.
Start engine and allow air pressure to build to normal operating pressure.
d.
Stop engine and observe secondary air pressure gauge.
e.
If pressure gauge indicates a steady loss of pressure, system is leaking.
CONDITION/INDICATION
DOES AIR SYSTEM LEAK WITH SHIFT LEVER IN HIGH POSITION?
DECISION
YES - Perform Secondary Pressure Gauge Reads No Pressure, Low Pressure, Or Builds To Normal Operating
Pressure Slowly troubleshooting (WP
0131).
NO - Go to Step (3).
TM 9-2320-272-23-1
0140
0140-3
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