JLG Telescopic Crawler Boom Lift 43 Fault Code: Tilt Up Open Fault
Also called Problems with the Engine
Tilt Up Open Fault · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault code 43 on JLG telescopic crawler boom lifts covers a group of engine-related problems reported through the machine's controller, plus a specific 'Tilt Up Open Fault' condition detected as an open circuit on pin J1-23. The exact meaning depends on which sub-condition triggered it, ranging from high engine temperature to low oil pressure to loss of alternator output.
High severity. Code 43 groups several engine protection faults (high temperature, low oil pressure, no alternator output) with a wiring open fault on the tilt circuit. Some of these, like low oil pressure or high engine temperature, can cause engine damage if ignored. The tilt open fault disables that function until the controller is power cycled.
What does JLG Telescopic Crawler Boom Lift error code 43 mean?
JLG lists code 43 under two descriptions: 'Problems with the Engine' and 'Tilt Up Open Fault.' This means the code is used as an umbrella for multiple distinct engine-related fault conditions and also for a wiring open detected on pin J1-23, which is tied to the tilt up circuit.
The engine-related sub-faults include high engine temperature, a clogged or bypassed air filter, no alternator output, low oil pressure, oil pressure sensor shorts (to battery or ground), coolant temperature sensor short to ground, passed-through Ford ECM fault codes, J1939 CANBUS engine fault messages (SPN/FMI), unrecognized Ford fault codes, loss of 485 communications with a Ford ECM, and fuel sensor shorts (to battery or ground).
The Tilt Up Open Fault portion is separate: it is set when the controller sees an open circuit on pin J1-23. Once this condition is detected, the fault is latched. There is no automatic reset, the controller must be powered down to clear it.
What triggers a JLG Telescopic Crawler Boom Lift 43 code?
JLG defines set conditions for each sub-fault: high engine temperature above 117°C on Ford engines or above 130°C on Deutz engines; no alternator output when the engine has run for 15 seconds or more and battery voltage is still below 11.5 volts; low oil pressure below 8 PSI after the engine has run at least 10 seconds on Deutz engines, or a Ford ECM-reported low oil pressure fault; oil pressure sensor short to battery when the sensor reads above 6.6 volts; oil pressure sensor short to ground when the sensor reads below 0.1 volts for more than 5 seconds (not checked during crank); coolant temperature sensor short to ground when reading below 0.1 volts; loss of 485 communications when no ECM response is received for 2.5 seconds; fuel sensor short to battery above 4.3 volts; fuel sensor short to ground below 0.2 volts. The Tilt Up Open Fault itself is set on an open circuit at pin J1-23.
Common causes of 43
- High engine temperature exceeding the threshold for the configured engine type (Ford or Deutz)
- Clogged or bypassed air filter restricting airflow to the engine
- Charging system failure resulting in no alternator output after startup
- Low engine oil pressure, either measured directly on Deutz engines or reported by the Ford ECM
- Oil pressure sensor wiring or sensor failure causing a short to battery or short to ground
- Coolant temperature sensor wiring failure causing a short to ground
- Fuel level or fuel pressure sensor wiring failure causing a short to battery or short to ground
- Passed-through Ford ECM fault codes, including unrecognized codes, surfacing through the machine's fault reporting
- Loss of 485 serial communications between the controller and a Ford ECM
- J1939 CANBUS engine control module reporting a fault via SPN and FMI codes
- An open circuit in the wiring harness or connector at pin J1-23 affecting the tilt up circuit
How to troubleshoot JLG Telescopic Crawler Boom Lift 43: first checks
- Check the engine coolant temperature gauge or diagnostic display against the listed thresholds for your engine type (Ford or Deutz) before assuming a sensor fault
- Inspect the air filter and housing for clogging or bypass condition
- With the engine running, verify charging voltage at the battery; if it stays below 11.5 volts past 15 seconds of run time, inspect the alternator, belt, and wiring
- Check engine oil level and pressure; on Deutz-configured machines confirm the reading against the 8 PSI threshold
- Inspect oil pressure sensor wiring and connector for corrosion or damage if a short-to-battery or short-to-ground condition is suspected
- Inspect coolant temperature sensor wiring for a short to ground if that fault is active
- Check fuel sensor wiring and connector for damage if a fuel sensor short fault is reported
- If a Ford or J1939 CANBUS fault is present, retrieve the specific Ford fault code or SPN/FMI pair from the display for further diagnosis
- For the Tilt Up Open Fault, inspect the wiring harness, connector pins, and continuity at pin J1-23 for an open circuit
How the code clears
JLG states the action for the Tilt Up Open Fault condition is 'None. Fault shall be latched and only reset upon power down of the controller.' This means once the open circuit at pin J1-23 is detected and repaired, the operator or technician must fully power down the controller to clear the latched fault; there is no separate reset procedure listed for the other engine sub-faults beyond correcting the underlying condition.
Frequently asked questions
What does JLG fault code 43 mean?
It is used for two different things: a set of engine problem faults (like high temperature, low oil pressure, or no alternator output) and a Tilt Up Open Fault caused by an open circuit on pin J1-23. Check the display text to see which condition applies.
Why won't fault code 43 clear after I fix the problem?
For the Tilt Up Open Fault, JLG's documented action is that the fault is latched and only resets when the controller is powered down. Fixing the wiring issue alone will not clear it; you need to cycle power to the controller.
Is fault code 43 dangerous to keep operating with?
It depends on the sub-fault. High engine temperature and low oil pressure can cause engine damage if ignored. A tilt up open fault will affect that specific function. Treat any active code 43 as a reason to stop and diagnose before continuing normal operation.
How do I know if my machine has a Ford or Deutz engine for these thresholds?
Check your machine's configuration or engine data plate. The thresholds JLG lists differ by engine: for example high temperature trips above 117°C on Ford engines versus above 130°C on Deutz engines.
What is pin J1-23 and why does it matter for this fault?
Pin J1-23 is the wiring connection point JLG's controller monitors for the tilt up circuit. An open circuit there, meaning no continuity, sets the Tilt Up Open Fault portion of code 43.
Can a bad alternator trigger fault code 43?
Yes. JLG lists 'No alternator output' as one of the engine problem conditions under code 43, triggered when battery voltage stays below 11.5 volts after the engine has run 15 seconds or more.
Does fault code 43 ever relate to a fuel sensor?
Yes. JLG lists fuel sensor short to battery (reading above 4.3 volts) and fuel sensor short to ground (reading below 0.2 volts) as two of the engine-related sub-faults grouped under code 43.