TM 9-2320-272-24-1
Table 2-4. Compressed Air and Brake System Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
22. COOLING FAN DOES NOT STOP RUNNING, ENGINE TEMPERATURE BELOW NORMAL OPERATING RANGE
(OVERRIDE BOLT NOT INSTALLED)
Replace fan drive clutch actuator (para. 3-73 or 3-74).
END OF TESTING!
23. FRONT WHEEL DRIVE DOES NOT ENGAGE (FRONT WHEEL DRIVE LOCK-IN SWITCH ENGAGED AND
TRANSFER CASE SHIFT LEVER IN HIGH POSITION)
Test 1. Isolate malfunction.
Shift transfer case shift lever in LOW position.
a. If front wheel drive continues to malfunction, perform test 2.
b. If front wheel drive operates, perform test 5 and 6.
Test 2. Inspect for air leakage in air system.
Step 1. Shift transfer case lever in HIGH position and engage front wheel drive lock-in switch.
Step 2. Start engine and allow air pressure to build to normal operating pressure.
Step 3. Stop engine.
Step 4. Observe secondary air pressure gauge.
a. If gauge indicates a steady loss of air, perform malfunction 14.
b. If gauge indicates no loss of air, proceed to step 5.
Step 5. Shift transfer case lever in LOW position and observe secondary air pressure gauge.
a. If gauge indicates a steady loss of air, perform tests 3 and 4.
b. If gauge indicates no loss of air, perform tests 7 and 8.
Test 3. Inspect air line (2) from actuator valve (1) to transfer case (transfer case shift lever in LOW
position, secondary air pressure gauge indicates steady loss of air).
a. If leakage is present, repair or replace air line (2) (TM 9-243).
b. If no leakage is present at air line (2), perform test 4.
Test 4. Inspect supply line (3) for leakage (transfer case shift lever in LOW position, secondary air
pressure gauge indicates steady loss of air).
a. If leakage is present, repair or replace air line (3) (TM 9-243).
b. If no leakage is present at air line (3), notify DS maintenance of defective actuator
valve (1).
Test 5. Check for air pressure at air line (4) from actuator valve (1) to front wheel drive lock-in
switch (front wheel drive functions with transfer case shift lever in LOW position, but does
not function with transfer case lever in HIGH position and front wheel drive lock-in switch
engaged ).
Step 1. Disconnect air line (4) from actuator valve (1) and connect test gauge to air line (4).
Step 2. Start engine, place transfer case shift lever in HIGH position, and engage front wheel
drive lock-in switch.
Step 3. Observe test gauge.
a. If air pressure is not indicated, perform test 6.
b. If air pressure is present, notify DS maintenance of defective actuator valve (1).
c. Stop engine, drain air, remove test gauge, and connect air line (4).
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