JLG Telescopic Crawler Boom Lift 33 Fault Code: Driver Problem
Driver Problem · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault code 33 on JLG Telescopic Crawler Boom Lifts is a Driver Problem fault at priority level 6, and item 33 in the list of communicated driver circuit faults corresponds specifically to a two speed short to battery condition on the machine's output driver circuit. It means the controller has detected the two speed circuit reading a voltage consistent with an unintended connection to battery power instead of switching normally.
Medium severity. This is listed at priority 6, which places it among the lower-urgency driver fault codes rather than an immediate shutdown condition. Still, a shorted two speed output can affect travel speed control and should be diagnosed before continued operation.
What does JLG Telescopic Crawler Boom Lift error code 33 mean?
Fault code 33 falls under the broader 'Driver Problem' fault category used by JLG's controller to flag issues with output driver circuits, which are the electrical paths that switch power to solenoids, relays, and other actuators on the machine.
Within this category, the numbered list of communicated faults identifies exactly what condition triggered the alert. Item 33 specifically identifies a 'two speed short to battery' condition, meaning the wiring or driver circuit responsible for controlling the machine's two-speed travel function is detecting voltage where it should not, consistent with a short to the battery supply.
This is an electrical driver fault tied to the travel/drive system rather than a hydraulic or engine fault. The controller reports this so technicians can distinguish it from similar faults like an open circuit or a short to ground on the same two speed circuit.
Common causes of 33
- A wire in the two speed circuit has chafed, pinched, or rubbed through insulation and is now touching a battery-voltage wire.
- A short internal to the two speed solenoid or relay is allowing battery voltage to feed back into the control circuit.
- Corrosion or water intrusion at a connector in the two speed circuit is bridging the signal wire to a nearby power source.
- A wiring harness repair or aftermarket splice was made incorrectly, connecting the two speed wire to a constant power source.
How to troubleshoot JLG Telescopic Crawler Boom Lift 33: first checks
- Inspect the wiring harness along the two speed circuit route for visible chafing, pinch points, or exposed conductor touching another wire.
- Check the two speed solenoid or relay connector for corrosion, moisture, or damaged pins, and disconnect it to see if the fault clears.
- With the connector disconnected, test the two speed circuit wire for voltage; if battery voltage is present with the connector unplugged, the short is in the harness, not the solenoid.
- Trace the harness back toward the battery and main power distribution point, looking for any splice or connector where the two speed wire could contact a battery-fed wire.
- Check other driver circuits that share connectors or harness routing with the two speed circuit for the same type of fault, since a single chafe point can affect multiple circuits.
How the code clears
No separate clearing step is listed for this code. Once the short to battery condition is repaired, the fault should stop being reported the next time the controller checks the two speed circuit during normal operation or self test.
Frequently asked questions
What does fault code 33 mean on a JLG Telescopic Crawler Boom Lift?
It means the controller detected a 'two speed short to battery' condition, which is one of the numbered Driver Problem faults JLG's system reports. The two speed circuit, which controls switching between travel speed ranges, is reading battery voltage when it should not be.
Is fault code 33 an emergency stop condition?
It is listed at priority 6, which is a lower-urgency driver fault rather than a critical shutdown code. However, because it affects the travel speed control circuit, it should be diagnosed before returning the machine to normal service.
Can I keep operating the lift with fault code 33 active?
It depends on how the two speed function is affected in practice. Since this fault relates to the travel drive circuit, operators should have it checked promptly rather than continuing to rely on that function without inspection.
What is the difference between fault 33 and other two speed faults?
The same two speed circuit can report three distinct conditions: open circuit, short to ground, or short to battery. Fault 33 specifically identifies the short to battery variant, meaning excess voltage is present on the circuit rather than a break or a ground short.
What usually causes a short to battery on a driver circuit like this?
Common causes include chafed wiring contacting a power-fed wire, corrosion bridging connector pins, an internal short in the solenoid or relay itself, or an incorrect wiring splice made during a previous repair.
How do I clear fault code 33 after repair?
No separate clearing step is listed for this code. Once the short is repaired, the controller should stop reporting the fault during normal operation or the next self test cycle.
Does fault code 33 affect anything besides two speed travel?
The fault itself is specific to the two speed circuit, but a wiring short of this kind can sometimes affect nearby circuits sharing the same connector or harness routing, so it is worth checking related driver circuits during diagnosis.