TM 5-5420-280-23&P
0010 00
Hydraulic System Troubleshooting (Contd).
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
6. BOTTOM BRIDGE HALF WILL NOT MOVE TO REAR (L5-A) OR (R17-H) (CONTD)
If all lights are lit on control valve solenoids, check limit switch KA2 to see if damaged or
out of adjustment. Adjust or replace limit switch KA2. Refer to WP 0056 00.
Step 3. Check for damaged control valves KY1, KY4, and KY23.
a. Manually operate control valves by locking KY1 control valve in on position and
depressing KY4 to operate front pin wheel drive and KY23 to pay-out winch cable.
b. If control valve operates, refer to malfunction 10 in Electrical System Troubleshooting
Step 4. Check that forward pin wheel drive hydraulic motor rotates.
If hydraulic motor will not rotate, replace hydraulic motor. Refer to WP 0084 00.
END OF TESTING
7. LAUNCH BOOM WILL NOT LOWER OR RAISE (L6-A), (L12-A), (L15-A), (L20-H), OR (R4-A+H+M), (R11-A),
(R9-A), (R16-A)
Step 1. Check if both launch boom retaining pins are installed.
Remove launch boom retaining pin. Refer to TM 5-5420-280-10.
Step 2. Check for missing retaining plate and pin on launch boom and main shaft.
a. Replace missing retaining plate and pin on launch boom and main shaft. Refer to
b. Replace four hydraulic fillings on main shaft if pin was missing. Refer to WP 0095 00.
Step 3. Check for damaged hydraulic tubing.
Repair or replace damaged hydraulic tubing. Refer to WP 0069 00.
Step 4. Check for damaged bearing shaft manifold.
Replace damaged bearing shaft manifold. Refer to WP 0092 00.
Step 5. Check that KY1, KY18, and KY19 hydraulic control valve solenoid LED lights are lit when
action button 1 or 2 is depressed.
NOTE
Potentiometer JR2 is used to stop launch boom at a set position in
the launching procedures.
If both lights are lit on control valve solenoids, check potentiometer JR2 position 6 to see if
damaged or out of adjustment. Adjust or replace potentiometer JR2. Refer to WP 0093 00.
END OF TESTING
8. LAUNCH BOOM WILL NOT STOP AT COUPLING POSITION (L14-A), (L15-A) OR (R9-A)
Step 1. Check that KY1 and KY16 hydraulic control valve solenoid LED lights are lit when action
button 1 is depressed.
NOTE
Potentiometer JR2 is used to stop launch boom at a set position in
the launching procedures.
If all lights are lit on control valve solenoids, check potentiometer JR2 position 4 to see if
damaged or out of adjustment. Adjust or replace potentiometer JR2 (WP 0093 00).
Step 2. Check for damaged control valve KY1 and KY16.
a. Manually operate each control valve solenoid by depressing button on KY1 and KY16
control valves.
b. If control valves operate, refer to malfunction 19 in Electrical Troubleshooting
c. If either control valve will not operate, replace control valve. Refer to WP 0075 00.
END OF TESTING
