TM 5-2420-231-23-1
0077
Table 1. Backhoe Bucket Does Not Operate Correctly - Continued.
077
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Backhoe Bucket Does Not
Test Step 4. Check Pilot Control
Operate Correctly -
Pressure.
Continued
Perform pilot pressure test (WP 0086). Pilot Control Pressure 350 to 550 psi
- Disconnect hose and pressure gauge.
Proceed to Test Step 5.
Pilot Control Pressure Less Than 350
psi - Disconnect hose and pressure
gauge.
Replace pilot control valve assembly
(WP 0264).
Proceed to Test Step 6.
Test Step 5. Check Joystick Control.
1. Perform pilot control valve test
Any Pilot Control Flow Greater Than
1 gpm - Perform Flowmeter Disconnect
Procedure (WP 0086).
Replace backhoe control valve
assembly (WP 0263).
Proceed to Test Step 6.
Any Pilot Control Flow Less Than 1
gpm - Perform Flowmeter Disconnect
Procedure (WP 0086).
Replace left-side joystick control valve
assembly (WP 0266).
Proceed to Test Step 6.
2. Check output of rear section (WP
Efficiency of Pump Less Than 70
Percent - Turn ignition switch to the off
position (TM 5-2420-231-10).
Perform Flowmeter Disconnect
Procedure (WP 0086).
Replace hydraulic oil pump (WP 0230).
Proceed to Test Step 6.
Efficiency of Pump Is 70 Percent or
Greater - Turn ignition switch to the off
position (TM 5-2420-231-10).
Perform Flowmeter Disconnect
Procedure (WP 0086).
Replace left-side joystick control valve
assembly (WP 0266).
Proceed to Test Step 6.
Test Step 6. Verify That Symptom Is
Resolved.
Operate backhoe bucket (TM 5-2420-
Backhoe Bucket Cylinder Operates
231-10). Monitor and record machine
Normally - Troubleshooting complete.
operation.
Backhoe Bucket Cylinder Operates
Slowly or Will Not Operate - Repeat
troubleshooting from the beginning.
END OF WORK PACKAGE
0077-5/(6 blank)
