JLG Articulating Boom Lift 35 Fault Code: Brake Pressure Problem
Also called APU Active, Intake Air Temperature (lAT) Sensor High Voltage, Speed Warning (With Thrust Mode Operation)
Brake Pressure Problem · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault code 35 (SPN / FMI 14) on a JLG articulating boom lift is a functional fault warning tied to several different conditions depending on the machine and mode: engine revolutions above the top speed limit while thrust mode is active, emergency descent mode being active, or a brake pressure problem where brakes fail to lock or fail to release. Because the code covers multiple descriptions, the correct fix depends on which condition is actually present on your machine.
High severity. This code can point to a brake pressure fault, which is a safety-critical condition. It can also appear during emergency descent mode or a speed-limit/thrust mode event. Treat any brake-related trigger as high priority and stop travel or lift operation until it is confirmed safe.
What does JLG Articulating Boom Lift error code 35 mean?
Fault code 35 is used by JLG across a few different fault descriptions, so what it means on your machine depends on which condition is active. One version relates to revolutions being above the top revolution speed limit while a thrust mode function is active, which is a functional fault warning rather than a hard failure code.
Another version of this code appears when emergency descent mode is active. In that case the code is really just flagging that the machine is running in its emergency descent function, and the fix is simply to stop using that mode.
A third version covers a brake pressure problem, which can mean one of two things: the brakes did not lock because brake pressure did not clear when the brake valve was de-energized, or the brakes did not release because no brake pressure was detected when the pump motor was running and the brake valve was energized. Brake circuits are safety-critical, so this version of the code deserves the most caution.
Common causes of 35
- Revolutions above the top revolution speed limit while thrust mode function is active (functional fault warning, no distinct remarks given).
- Emergency descent mode active on the machine.
- Brakes did not lock: brake pressure did not clear when the brake valve was de-energized.
- Brakes did not release: no brake pressure was detected when running the pump motor and energizing the brake valve.
How to troubleshoot JLG Articulating Boom Lift 35: first checks
- Confirm which condition is present: check whether the machine is in emergency descent mode, whether thrust mode/speed limit is involved, or whether the fault is tied to brake pressure behavior.
- If thrust mode / speed related: check parameters, check speed settings, and check PID setting.
- If thrust mode / speed related: check rods, check the actuator and replace if required, and check the cable to the actuator.
- If thrust mode / speed related: check the speed sensor for impulses on incorrect speed, and check the number of teeth on the sensor wheel.
- For vehicles, check for possible thrust mode engagement as a contributing factor.
- If emergency descent mode is active, stop using emergency descent mode as the corrective action.
- If brake pressure is involved, check for brake pressure not clearing when the brake valve is de-energized (brakes did not lock) or no brake pressure detected when the pump motor runs and the brake valve is energized (brakes did not release).
How the code clears
No single reset procedure is listed for this code, since it covers several different fault descriptions. For the thrust mode/speed limit version, the fix involves working through the listed parameter, actuator, cable, and speed sensor checks. For the emergency descent mode version, the corrective action given is simply to stop using emergency descent mode. No separate clearing step is listed for the brake pressure problem description beyond correcting whichever brake lock/release condition is present.
Frequently asked questions
What does JLG fault code 35 mean?
It depends on which description applies to your machine. It can mean revolutions went above the top speed limit while thrust mode was active, that emergency descent mode is active, or that there is a brake pressure problem where the brakes either did not lock or did not release.
Is fault code 35 dangerous to keep operating with?
Any version involving brake pressure should be treated as high priority since it affects the machine's ability to lock or release brakes correctly. The emergency descent and thrust mode versions are functional fault warnings, but you should still confirm the actual cause before continuing normal operation.
Why is my JLG boom lift showing this code when I use emergency descent mode?
This is expected behavior tied to that description of code 35. The listed corrective action is to stop using emergency descent mode, which should clear that condition.
What is thrust mode and why does it trigger this code?
The listed cause is that revolutions were or are above the top revolution speed limit while a 'thrust mode' function is active. JLG's help steps direct you to check parameters, speed settings, PID setting, rods, the actuator, the cable to the actuator, and the speed sensor, and to check for possible thrust mode engagement on the vehicle.
What causes the brake pressure version of fault code 35?
Two conditions are listed. Brakes did not lock because brake pressure did not clear when the brake valve was de-energized, or brakes did not release because no brake pressure was detected when running the pump motor and energizing the brake valve.
Do I need to replace the actuator if I get this code?
Only if inspection shows it is faulty. The listed help steps say to check the actuator and replace it if required, after first checking parameters, speed settings, PID setting, rods, and the cable to the actuator.
Can a bad speed sensor cause fault code 35?
Yes, JLG's help steps include checking the speed sensor for impulses on incorrect speed and checking the number of teeth, since a faulty sensor reading can make the controller think revolutions are above the top speed limit.