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The JLG 45IC and Its Hybrid Configuration
The JLG 45IC is a unique boom lift model that blends features from electric and internal combustion platforms. Built on the chassis of the JLG 40 electric series, the 45IC incorporates a dual-fuel engine and a 45-foot articulating boom with a 5-foot jib. This hybrid design was intended to offer extended reach and flexible power options for indoor and outdoor applications. However, its limited production and unconventional control architecture have made troubleshooting more complex than with standard models.
Symptoms of Drive Failure
Operators have reported that the lift functions—boom articulation, rotation, and elevation—work normally, but the machine refuses to move when the drive joystick is engaged. The engine does not respond, and there is no load increase or hydraulic activation. This points to a failure in the drive control logic rather than a mechanical or hydraulic issue.
Horsepower Control Card and Its Role
At the heart of the issue is the Horsepower Control Card, a circuit board mounted inside the basket control box. Its primary function is to monitor engine RPM and regulate voltage to the drive controller. When the engine encounters increased load—such as driving uphill—the card reduces voltage to the drive valves to prevent stalling. This dynamic adjustment is critical for maintaining smooth operation across varying terrain.
When the card is bypassed using a jumper connector, the machine regains drive function, albeit in low-speed mode. This confirms that the card is interrupting the signal path, either due to faulty input, poor grounding, or internal malfunction.
Troubleshooting the HP Card
Several diagnostic steps can help isolate the problem:
Precision Governor and Engine Control
Adjacent to the engine is the Precision Governor Control Box, which adjusts throttle settings via potentiometers labeled LOW, MID, and HIGH. While this box does not directly control the HP card, its settings influence engine RPM, which in turn affects the card’s behavior. Ensuring proper calibration of the governor is essential for consistent RPM delivery.
Manufacturer Support and Legacy Challenges
The 45IC was a transitional model and never achieved widespread adoption. As a result, documentation is sparse, and many service technicians are unfamiliar with its architecture. JLG’s official manuals caution against adjusting the HP card, as it is factory-calibrated and sealed. However, some repair services have successfully recalibrated the card by removing the sealant and tuning the internal pots.
Conclusion
Drive failure in the JLG 45IC is frequently caused by issues with the Horsepower Control Card, particularly when it fails to receive or process engine RPM signals. While bypassing the card restores basic movement, it eliminates dynamic load protection and risks engine stalling. A thorough inspection of wiring, grounding, and signal inputs is essential before replacing or recalibrating the card. Given the model’s rarity, technicians must approach repairs with patience, precision, and a willingness to trace unconventional signal paths.
The JLG 45IC is a unique boom lift model that blends features from electric and internal combustion platforms. Built on the chassis of the JLG 40 electric series, the 45IC incorporates a dual-fuel engine and a 45-foot articulating boom with a 5-foot jib. This hybrid design was intended to offer extended reach and flexible power options for indoor and outdoor applications. However, its limited production and unconventional control architecture have made troubleshooting more complex than with standard models.
Symptoms of Drive Failure
Operators have reported that the lift functions—boom articulation, rotation, and elevation—work normally, but the machine refuses to move when the drive joystick is engaged. The engine does not respond, and there is no load increase or hydraulic activation. This points to a failure in the drive control logic rather than a mechanical or hydraulic issue.
Horsepower Control Card and Its Role
At the heart of the issue is the Horsepower Control Card, a circuit board mounted inside the basket control box. Its primary function is to monitor engine RPM and regulate voltage to the drive controller. When the engine encounters increased load—such as driving uphill—the card reduces voltage to the drive valves to prevent stalling. This dynamic adjustment is critical for maintaining smooth operation across varying terrain.
When the card is bypassed using a jumper connector, the machine regains drive function, albeit in low-speed mode. This confirms that the card is interrupting the signal path, either due to faulty input, poor grounding, or internal malfunction.
Troubleshooting the HP Card
Several diagnostic steps can help isolate the problem:
- Check ground continuity: A poor ground connection can prevent the card from functioning correctly.
- Verify RPM signal: The card relies on an RPM input from the engine, possibly via a crankshaft or flywheel sensor. If this signal is missing or corrupted, the card may default to a fail-safe mode.
- Inspect boom cable wiring: The RPM signal may travel through the boom harness. Damaged wires or corroded connectors can disrupt communication.
- Test voltage output: Measure the card’s output voltage at idle and high RPM. If readings remain static, the card may not be processing input correctly.
- Review foot switch and limit switches: These safety interlocks can disable drive functions if not engaged properly.
Precision Governor and Engine Control
Adjacent to the engine is the Precision Governor Control Box, which adjusts throttle settings via potentiometers labeled LOW, MID, and HIGH. While this box does not directly control the HP card, its settings influence engine RPM, which in turn affects the card’s behavior. Ensuring proper calibration of the governor is essential for consistent RPM delivery.
Manufacturer Support and Legacy Challenges
The 45IC was a transitional model and never achieved widespread adoption. As a result, documentation is sparse, and many service technicians are unfamiliar with its architecture. JLG’s official manuals caution against adjusting the HP card, as it is factory-calibrated and sealed. However, some repair services have successfully recalibrated the card by removing the sealant and tuning the internal pots.
Conclusion
Drive failure in the JLG 45IC is frequently caused by issues with the Horsepower Control Card, particularly when it fails to receive or process engine RPM signals. While bypassing the card restores basic movement, it eliminates dynamic load protection and risks engine stalling. A thorough inspection of wiring, grounding, and signal inputs is essential before replacing or recalibrating the card. Given the model’s rarity, technicians must approach repairs with patience, precision, and a willingness to trace unconventional signal paths.
