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JLG 800A 800AJ troubleshooting guide

1.Excessive Noise and/or Vibration

  • Item: Check oil level in reservoir and oil supply to the motor.
  • Description:  Insufficient hydraulic fluid could lead to cavitation that would cause system noise.
  •  Action: Fill the reservoir to the proper level and ensure that oil supply to the motor is adequate and the lines are unobstructed.
  • Item: Check for air in the system.
  • Description:  Air trapped within the system lines, or the motor itself, could  result in cavitation that would cause system noise.
  •  Action:  Ensure that all of the system lines and components are purged  of air
  • Item: Ensure that all of the system lines and components are purged of air
  • Description:  A loose or incorrect shaft coupling will produce vibrations that could result in system noise.
  •  Action: Ensure that the correct coupling is used and that it fits properly onto the shaft.
  • Item: Inspect the output shaft alignment.
  • Description: Misaligned shafts create excessive frictional vibration that could result in system noise
  •  Action: Ensure that the shafts are properly aligned.
  • Item: Hydraulic oil viscosity above limits.
  • Description: Viscosity above acceptable limits will result in cavitation that would lead to system noise.
  • Action: Viscosity above acceptable limits will result in cavitation that would lead to system noise.

2. System Operating Hot

  • Item: Check oil level in reservoir and oil supply to the pump.
  • Description: Insufficient amount of hydraulic fluid will not meet the cooling demands of the system.
  • Action: Fill the reservoir to the proper level.
  • Item: Inspect the heat exchanger, (if so equipped).
  • Description: If the heat exchanger fails, or becomes obstructed, it may not meet the cooling demands of the system.
  • Action: Ensure that heat exchanger is receiving adequate air flow and that the heat exchanger is in good operating condition. Repair or replace as necessary.
  • Item: Check the system relief valves.
  • Description: If a system relief valve becomes unseated for an extended period of time or fails for any other reason, the system could become overheated.
  • Action: If a system relief valve becomes unseated for an extended period of time or fails for any other reason, the system could become overheated.

 3. Won’t Shift or Slow to Start

  • Item: Check the signal line to the servo control port.
  • Description:  Obstructed or restricted flow through the servo control signal lines could result in slow shift or no shift conditions within the motor.
  • Action: Ensure that the signal lines are not obstructed or restricted and that signal pressure is adequate to shift the motor.
  • Item: Ensure that the signal lines are not obstructed or restricted and that signal pressure is adequate to shift the motor.
  • Description: Supply and drain orifices determine the shift rate of the motor. The smaller the orifice, the longer the time it takes to shift the motor. Obstruction will also increase shift times.
  • Action: Ensure that the proper control orifices are installed in the motor and verify that they are not obstructed. Clean or replace as necessary.

4.  CHASSIS & TURNTABLE

We will discuss Troubleshooting in two general categories:

• Governor won’t work.
• Governor works, but can’t be set up to give satisfactory performance.

There is, of course, some overlap between these categories. Read both sections and apply the fixes that seem appropriate.

OTE: During troubleshooting, be prepared to control the engine manually to prevent overspeeds, etc.
• Governor won’t work.
No reaction from Governor. Actuator output arm never moved, engine off or engine running. Can be caused by:

  1. No power.
  2.  Incorrect linkage, preventing movement.
  3. Incorrect electrical hook-up
  4. No speed signal to Governor.
  5. Damaged Controller or Actuator.

(1.) No power – Use a multimeter to check for 12-15 VDC between terminals A & B on the controller. Check during engine off and engine running conditions. If voltage is absent or low, check for:

a. Wiring error.
b. Hook-up on wrong side of ballast resistor.
c. Low battery.
d. Bad voltage regulator.
e. Bad ground connection.
f. corroded terminals.
g. Undersized wiring.

(2.) Incorrect Linkage – Re-check linkage. The freedom of movement and lack of play are important.

(3.) Incorrect Electrical Hook-up – Re-check all wiring and connections to the Actuator and Controller against the supplied schematic.
(4.) No speed signal to Controller

a. Check the voltage between terminals C and ground and D and ground of the 8 pin connector with the engine running. You should see 5 – 30 VDC.
b. The above checks do not guarantee a good speed signal, but their absence proves that there is a problem.

(5.) Incorrect Electrical Hook-up – If steps 1 – 4 above have not revealed the problem, the governor may have been damaged, either in shipping or during hook-up and test.

• Governor reacts, but can’t be set up to give proper performance.

This kind of trouble usually falls into three main categories

1. Actual Governor malfunction.
2. Governor installation problems and improper adjustment.
3. Governor not tuned or adjusted for engine/application.
NOTE:Assure the engine is operating properly by running engine manually. The Governor will not control any poor running engine.

(1.) Actual Governor Malfunction – The Governor was engine-tested for proper operation just prior to being shipped. Unless damaged in shipment or by improper handing, it should be serviceable. To check for proper operation proceed as follows

a. Once again, disconnect fuel system linkage from Governor output arm and control engine manually.
b.Start engine, hold at a low speed, Governor arm should move to full-fuel position.
c. Increase engine speed carefully. At some engine speed, Governor arm should move to low-fuel position.
d.By carefully varying engine speed, you should be able to cause the Governor arm to pause
momentarily near the middle of its travel. This engine speed is the speed for which the Governor is adjusted. If grossly incorrect, reset High Engine Pot.
e. With the engine running at low speed, move the Governor arm throughout its stroke by hand. You should feel a constant smooth force in the on direction. No binding or rubbing should be felt within the Governor.

If steps 1a. thru 1e. can be accomplished as described, the Governor is probably OK. It recognizes underspeed, overspeed, onspeed and is not binding internally. If the above steps cannot be accomplished satisfactorily, there is probably an actual Governor malfunction

a. Governor is unable to move fuel system freely (not enough Actuator force available). If Governor doesn’t move fuel system to on far enough to provide sufficient fuel but Governor arm moves far enough when disconnected look for:

1. Linkage binding or misadjusted.
2. Low voltage at Governor during operation.

(3.) Governor not tuned or adjusted for engine/application.

The basic adjustment to set sensitivity/stability is the Gain pot. A good starting point for many engines is full CCW, then CW 1/3 turn. (See “Governor adjustment” section). To increase stability, turn CCW. If satisfactory governing cannot be achieved with this one adjustment, the factory adjustment may be needed. Normal starting point for this adjustment is fully CCW, then CW 1/4 turn. (Before changing this pot, mark the original position).

5. UMS TROUBLESHOOTING AND FAULT MESSAGES – NON-ADE MACHINES

Tower Lift Down Permanently closed

2/2 FUNCTION LOCKED OUT – TOWER LIFT DOWN PERMANENTLY CLOSED

The control system shall illuminate lamps and sound the alarm at startup for one second on and one second off. If the control system detects the TOWER LIFT DOWN, it shall report a fault. The TOWER LIFT DOWN function shall be locked out and activate the ground boom malfunction indicator lamp, upright tilted lamp and platform alarm continually until the condition is cleared.

Solution:
• Inspect switch and harness. Voltage (≈12V) should only be present on J1-3 of the UMS module when Tower Down switch is closed.

Backward Stability Concern Message

2/5 UMS SENSOR BACKWARD LIMIT REACHED

When the upright angle relative to the turntable is higher than +2.5° (away from the work platform), tower lift down shall be disallowed immediately. Tower Lift Down shall be re-allowed when the upright angle relative to the turntable is less than 2.0°. If Tower Lift Down is disabled for more than 1.5 seconds, the ground boom malfunction indicator lamp, upright tilted lamp and platform alarm shall light/ sound continually and a fault shall be raised. These conditions shall be latched along with Tower Lift Down until the upright angle is less than 2.0°for 2 seconds and the Tower Lift Down command is returned to neutral.

Solution:
• Inspect sensor mounting.
• Verify sensor calibration on level pad.
• Follow the corrective action listed on decal 1702265 located near the red knob of the machine.
• Inspect machine hydraulics.

Forward Stability Concern Message

2/5 UMS SENSOR FORWARD LIMIT REACHED

When the upright angle relative to the turntable is less than –4.0° for longer than 1.5 seconds, the ground boom malfunction indicator lamp, the platform distress lamp, and platform alarm shall light/sound continually and a fault shall be raised. The light/alarm signal shall be removed only when the upright angle reaches values greater than –3.0° for 2 seconds.

Solution:

• Inspect sensor mounting.
• Verify sensor calibration on level pad.
• Tower lift down.
• Inspect machine hydraulics.

UMS Out of Usable Range Message

2/5 UMS SENSOR OUT OF USABLE RANGE

When both the Turntable tilt sensor and the UMS sensor read greater then ±10°in the same direction the UMS shall be disengaged until the condition no longer exists and a fault shall be raised.

 

Solution:

• Verify the message clears when operating the machine on grade less than 10°.
• Inspect sensor mounting.
• Verify sensor calibration on level pad

Battery voltage < 9.0 Volts

4/4 SYSTEM VOLTS HIGH
Battery voltage is above 16V.
Solution:
• Inspect battery and alternator output.

UMS Sensor Not Calibrated Message

8/1 UMS SENSOR NOT CALIBRATED

If the control system detects a sensor out of range condition or a not calibrated fault with the UMS angle sensor, the control system shall report a fault and disable Tower Lift Down and activate the ground boom malfunction indicator lamp, upright tilted lampand platform alarm continually. If the control system detects that either angle sensor has not been calibrated, the ground boom malfunction lamp will flash at a 3 Hz rate until the system is calibrated or disabled.

Solution:

• Calibrate sensor.

 

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2 Comments

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