Load Capacity Envelope Exceeded, Boom Cutout Active
What does JLG-TH-6029-15 mean?
The JLG-TH-6029-15 (JLG Telehandler ADE Controller) diesel fault code means: Load Capacity Envelope Exceeded, Boom Cutout Active. This is a serious severity code.
Common Symptoms
- The instrument cluster LCD displays SPN 6029 FMI 15 and an alarm sounds
- Boom-up and boom-extend functions cut out mid-operation with no response from joystick
- A red overload indicator or capacity warning lamp illuminates on the dash
- The machine will still allow boom-down and boom-retract to reduce load moment
- Load percentage on the RCI display is at or above 100 percent
- Audible continuous beep or alarm tone sounds when the cutout activates
- Operator may notice sluggish boom response just before full cutout triggers
Probable Causes (Ranked by Likelihood)
- Actual load on forks exceeds the rated capacity for the current boom angle and extension combination per the load chart Very Likely
- Incorrect load chart selected in the ADE controller for the attachment or configuration in use (for example, work platform mode vs forks mode) Likely
- Faulty or out-of-calibration boom angle sensor providing incorrect angle data to the RCI system, causing a false overload condition Likely
- Faulty or out-of-calibration boom extension (length) sensor sending incorrect reach data to the load chart controller Likely
- Load cell or pressure transducer in the hydraulic lift circuit reading high due to contamination, damage, or drift, inflating the reported load Possible
- Damaged or pinched sensor wiring harness on the boom causing intermittent signal errors that trigger a false capacity fault Possible
- Operator bypassed a load chart safety interlock on a prior shift and the controller logged a latched fault that was not cleared Less Likely
Step-by-Step Diagnostic Procedure
Step 1. Before anything else, verify the actual load. Pull the forks back, set the boom to the position shown on the cab load chart placard, and compare the rated capacity at that angle and extension to the weight on the forks. If the load is genuinely over chart, this is an operator procedure issue, not a mechanical fault. Remove or redistribute the load.
Step 2. Verify the correct load chart mode is active in the ADE controller display. Use the JLG Analyzer software via the data link at the cab dash to confirm the machine is in the correct configuration mode (forks, jib, work platform). Switching modes with a load on the forks can trigger a false 6029-15.
Step 3. Inspect the boom angle sensor (typically mounted at the main pivot pin on the turret). Check for physical damage, cracked housing, or loose mounting hardware. With the boom at a known angle such as horizontal (0 degrees), navigate to the live sensor data screen in the JLG Analyzer software and confirm the angle reading matches actual. Spec is typically within plus or minus 1 degree.
Step 4. Inspect the boom extension sensor or cable-pull transducer along the boom. Extend the boom to a measured position, for example fully retracted and then to 10 feet. Confirm the instrument cluster LCD or JLG Analyzer software shows a matching extension value. A reading that jumps, sticks, or reads incorrectly points to a bad sensor or damaged cable reel.
Step 5. Check hydraulic pressure in the lift circuit. Connect a calibrated gauge to the lift cylinder port test point. Record pressure with a known test load and compare to the specification in the JLG service manual for that model. A pressure transducer reading significantly above actual pressure will cause the RCI to report an inflated load. Pressure transducers on JLG telehandlers are typically 0-5V output sensors. Measure signal voltage at the connector with a multimeter. Expect roughly 0.5V at no load and up to 4.5V at full rated pressure.
Step 6. Inspect the wiring harness along the full length of the boom for chafing, pinching at boom sections, or connector corrosion. Pay close attention to the harness wrap points on the inner and outer boom tubes where wear is most common. Wiggle the harness while watching the live data in JLG Analyzer software to catch intermittent faults.
Step 7. After correcting any sensor or load condition, clear the fault using the JLG Analyzer software via the data link at the cab dash. Cycle key power. Re-extend the boom through a full range of motion with a known load to confirm the RCI reads correctly and 6029-15 does not return.
Step 8. If all sensors read within spec and the fault persists with a confirmed in-chart load, the ADE controller load chart calibration may have drifted. This requires a full RCI calibration procedure using JLG Analyzer software and calibrated test weights. This step requires a JLG-authorized service shop with calibration weights and the EZcal or JLG Analyzer calibration module.
Frequently Asked Questions
What does JLG code 6029-15 mean on a telehandler?
It means the load sensing system detected that the combination of your current load weight, boom angle, and boom extension falls outside the approved load chart for this machine. The ADE controller cuts out boom-up and boom-extend to prevent a tip-over. You can still retract and lower the boom to get back into a safe zone.
Can I keep working with code 6029-15 active?
You can still retract and lower the boom, which the controller intentionally allows so you can recover from the overload condition. However, boom-up and boom-extend are cut out. You should not bypass or ignore this code. If the fault is a real overload, continuing to work risks a tip-over. If it is a sensor fault causing a false reading, the machine needs to be evaluated before returning to service.
How much does it cost to fix code 6029-15?
If the fault is a genuine operator overload, it costs nothing to fix. You just reduce the load or change the boom position to get back inside the chart. If it is a faulty sensor, expect $150-$400 for parts plus a few hours of labor at a shop. If the RCI system needs full recalibration with test weights, a JLG-authorized service shop will typically charge $300-$600 for that service.
Will the telehandler move and operate after I get this code?
Ground drive and steering remain active. The machine will travel. Boom-down and boom-retract also remain active so you can recover safely. Boom-up and boom-extend are locked out until the load moment drops back inside the chart and the fault is cleared. If the fault is caused by a bad sensor rather than a real overload, you will need to clear the code with JLG Analyzer software after the repair before full boom function returns.