Manitou MT 1840 False Overload Condition from LMI
Fault Codes & Symptoms
LMI indicates overload with no load or a light load. Related symptoms: - Erratic boom extension reading on the LMI display. - Sudden hydraulic lockout during operation. - LMI alarm sounds with no load. The machine is constantly in a lockout or warning state for overload, even with no load on the forks. It's unusable.
Confirmed cause: Damaged wiring for the boom extension sensor cable reel, causing intermittent and incorrect signals to the LMI controller. Repair performed: Repaired the damaged section of the boom extension sensor wiring harness. Protected the repaired area with a heavy-duty abrasion-resistant sleeve to prevent future chafing. Verification: Cycled the boom through its full range of motion (elevation, extension, retraction) multiple times. Monitored the LMI display to confirm that angle and extension readings were stable and accurate. Verified that no false overload warnings occurred. Technician notes: - The chafing occurred at a harness pass-through point. Check all harness routing and supports inside the boom sections during this repair. - Intermittent electrical issues in boom wiring are common. Wiggling sections of the harness while watching the live data can often pinpoint the location of the fault. - This fault could also be caused by a failing cable reel mechanism itself, causing signal loss.