JLG Articulating Boom Lift 45 Fault Code: Intake Air Temperature (lAT) Sensor Low Voltage
Also called Main Lift PVG Valve Command Improper, Main Lift PVG Valve Communications, Main Lift PVG Valve High Voltage, Main Lift PVG Valve Internal Fault, Main Lift PVG Valve Location Improper, Main Lift PVG Valve Low Voltage, Main Lift PVG Valve Obstructed, Main Lift PVG Valve Parameters Incorrect, Main Lift PVG Valve Sent Unrecognized Fault, Main Lift PVG Valve Setup Fault, Main Lift PVG Valve Stuck Extended, Main Lift PVG Valve Stuck Neutral, Main Lift PVG Valve Stuck Retracted, Main Lift PVG Valve Timeout, Main Lift PVG Valve Wiring Incorrect, Problems with the S-D CAN Based PVG Valves Currently Used on the 1250AJP Only, Tower Lift PVG Valve Command Improper, Tower Lift PVG Valve High Voltage, Tower Lift PVG Valve Internal Fault, Tower Lift PVG Valve Location Improper, Tower Lift PVG Valve Low Voltage, Tower Lift PVG Valve Obstructed, Tower Lift PVG Valve Parameters Incorrect, Tower Lift PVG Valve Send Unrecognized Fault, Tower Lift PVG Valve Setup Fault, Tower Lift PVG Valve Stuck Extended, Tower Lift PVG Valve Stuck Neutral, Tower Lift PVG Valve Stuck Retracted, Tower Lift PVG Valve Timeout, Tower Lift PVG Valve Wiring Incorrect, Tower Telescope PVG Valve Command Improper, Tower Telescope PVG Valve Communications, Tower Telescope PVG Valve High Voltage, Tower Telescope PVG Valve Internal Fault, Tower Telescope PVG Valve Location Improper, Tower Telescope PVG Valve Low Voltage, Tower Telescope PVG Valve Obstructed, Tower Telescope PVG Valve Parameters Incorrect, Tower Telescope PVG Valve Sent Unrecognized Fault, Tower Telescope PVG Valve Setup Fault, Tower Telescope PVG Valve Stuck Extended, Tower Telescope PVG Valve Stuck Neutral, Tower Telescope PVG Valve Stuck Retracted, Tower Telescope PVG Valve Timeout, Tower Telescope PVG Valve Wiring Incorrect
Intake Air Temperature (lAT) Sensor Low Voltage · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault code 45 covers a large group of PVG (proportional valve group) faults on the main lift, tower lift, and tower telescope hydraulic valves, including communication loss, internal faults, high/low excitation voltage, stuck spools, obstruction, improper commands, timeouts, setup faults, and wiring or location errors. It has a priority of 7 and always points to a problem with one of the three PVG valves or their wiring/calibration.
High severity. This code disables or degrades control of lift and telescope functions on the boom or tower. It should be diagnosed before returning the machine to normal lift operation, since a stuck or obstructed valve can mean loss of controlled movement.
What does JLG Articulating Boom Lift error code 45 mean?
Fault code 45 is not one single fault, it is a family of related faults tied to the PVG (proportional valve group) valves that control main lift, tower lift, and tower telescope hydraulic functions. Each specific message (communications lost, internal fault, high or low voltage, stuck spool, obstructed, command improper, timeout, setup fault, parameters incorrect, location improper, wiring incorrect) tells you which valve and which type of problem the controller detected.
These valves use CAN communication to receive position commands from the machine's control system and move a spool to direct hydraulic flow. If the valve loses communication, receives a bad command, cannot reach the commanded position, or reports a voltage or internal problem, the controller logs one of the code 45 variants and can restrict or stop the affected function.
A number of the variants relate specifically to valve setup and calibration: if the valve's stored spool data, location, or wiring does not match what the controller expects, it will flag a setup fault, parameters incorrect fault, location improper fault, or wiring incorrect fault. These are calibration and wiring issues rather than valve failures.
What triggers a JLG Articulating Boom Lift 45 code?
Several of the code 45 messages have explicit set conditions. A PVG valve timeout is set when the valve has not received a position command in 250 milliseconds. A power-up location or timing fault (main lift, tower lift, or tower telescope) is set when a different valve powers up during the allotted power-up window for that valve, or when the correct valve powers up outside its allotted power-up time window.
Common causes of 45
- CAN communication lost between the controller and the main lift, tower lift, or tower telescope PVG valve
- Internal fault reported by the PVG valve itself
- High or low excitation voltage detected at the valve
- Valve spool stuck in the neutral, extended, or retracted position
- Valve spool obstructed and unable to reach the commanded position
- Invalid or improper command received from the control system
- No position command received within the valve's timeout window
- Incorrect valve setup or calibration data, requiring a valve calibration
- Incorrect spool parameter data, requiring a valve calibration
- Valve hosed or wired incorrectly during calibration, causing a location improper fault
- Power wire for a given valve not actually connected to that valve, causing a wiring incorrect fault
- A different valve powering up during another valve's allotted power-up window, or a valve powering up outside its own window, due to a calibration or wiring problem
- Valve sending an unrecognized fault code that the controller cannot classify
How to troubleshoot JLG Articulating Boom Lift 45: first checks
- Identify which specific code 45 message is displayed (main lift, tower lift, or tower telescope, and which fault type) since this determines whether the issue is wiring, calibration, or a valve problem
- Check the physical valve locations and wiring against the known layout: main lift valve is at the lower left with a tan wire at position 55-50, tower lift valve is at the top left, center of three, with a tan wire at position 55-51, and tower telescope valve is at the top right with a brown wire at position 55-50
- Inspect connectors and harness wiring at each PVG valve for corrosion, looseness, or damage, especially the single labeled wire in each valve harness used to identify it during calibration
- Confirm the power wire for each valve is actually connected to that valve and not swapped with another valve's wiring
- If a setup, parameters incorrect, or location improper fault is present, plan on performing a valve calibration after confirming wiring is correct
- Check for mechanical obstruction or binding on the valve spool if a stuck or obstructed message is shown
- Verify CAN wiring and connections if a communications fault is shown for any of the three valves
How the code clears
No separate clearing step is listed beyond correcting the underlying wiring, connection, or calibration problem. Faults tied to setup, parameters incorrect, or location improper require a valve calibration to resolve. Faults tied to wiring incorrect or power-up timing require correcting the physical wiring before the fault will clear.
Frequently asked questions
What does JLG fault code 45 mean?
It means the controller has detected a problem with one of the PVG (proportional valve group) valves that runs main lift, tower lift, or tower telescope functions. The exact message, such as stuck spool, low voltage, or communications lost, tells you which valve and which type of problem is present.
Is fault code 45 the same for main lift, tower lift, and tower telescope?
No. Code 45 covers separate messages for each of the three valves (main lift, tower lift, tower telescope), each with its own set of possible fault types like internal fault, high voltage, low voltage, stuck neutral, stuck extended, stuck retracted, obstructed, command improper, timeout, setup fault, parameters incorrect, location improper, and wiring incorrect.
Why would a PVG valve show a location improper or wiring incorrect fault?
These faults happen when a valve was hosed or wired incorrectly during calibration, or when the power wire for a given valve is not actually connected to that valve. Each valve has a specific location and a labeled wire in its harness used to confirm identity during setup.
Does fault code 45 always mean the valve is bad?
Not necessarily. Many of the code 45 variants trace back to wiring, calibration, or communication problems rather than a failed valve. Setup fault, parameters incorrect, and location improper messages specifically point to calibration or wiring issues that require a valve calibration to fix.
What is the timeout condition for a PVG valve?
A PVG valve timeout fault is set when the valve has not received a position command within 250 milliseconds.
Where are the main lift, tower lift, and tower telescope PVG valves located?
The main lift valve is at the lower left with a tan wire at position 55-50. The tower lift valve is at the top left, center of three valves, with a tan wire at position 55-51. The tower telescope valve is at the top right with a brown wire at position 55-50.
Can I keep operating the machine with fault code 45 active?
It depends on which specific fault is active, but since these faults affect lift and telescope control, the safest approach is to stop and diagnose before continuing normal lift operation, especially if a stuck or obstructed spool message is shown.