JLG Scissor Lift 7 Fault Code: Charge Air Pressure
Also called Driving at Cutback - Pot-Hole Still Engaged
Charge Air Pressure · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
Fault code 7 on JLG scissor lifts (SPN 102 / FMI 2) means the control system detected that the pot-hole protection (PHP) mechanism did not retract while stowed, so drive speed is cut back until the issue clears. It can also relate to a charge air pressure sensor fault where the associated monitoring function gets de-activated.
Medium severity. The machine is not disabled but drive speed is intentionally reduced (cutback) as a safety measure until the pot-hole protection mechanism is confirmed retracted. Operating at cutback speed for an extended period is a workaround, not a fix.
What does JLG Scissor Lift error code 7 mean?
Fault code 7 (SPN 102 / FMI 2) covers two related conditions in JLG's diagnostic text. The main description ties it to the pot-hole protection (PHP) mechanism: while the machine is stowed, the control system checks that the PHP mechanism retracts properly. If it fails to retract, the controller limits drive speed to cutback as a protective measure.
A second body under the same code references a charge air pressure sensor fault, filed under the general 'Sensors' fault group. In that context, the fault indicates a short circuit or cable break at the sensor entry, and when this happens the associated monitoring function tied to that sensor is de-activated until repaired.
In practical terms for scissor lift operators, this code shows up as reduced travel speed with no obvious explanation, since the PHP mechanisms are meant to work automatically as the lift stows and unstows.
Common causes of 7
- Obstruction around the pot-hole protection mechanism preventing it from retracting fully
- PHP switch not securely mounted, causing an inconsistent or missing retract signal
- Faulty or damaged wiring between the PHP switches and the ground board
- Short circuit or cable break at the corresponding sensor entry (charge air pressure sensor path)
How to troubleshoot JLG Scissor Lift 7: first checks
- Inspect around both left and right pot-hole protection mechanisms for debris, mud, or physical obstructions blocking retraction
- Confirm both PHP switches are securely mounted and have not shifted or loosened
- Check PHP switch wiring from the ground board for damage, corrosion, or loose connectors, and verify proper switch operation: left PHP input is 24V at J1-9 with output 24V when deployed at J1-10, right PHP input is 24V at J1-17 with output 24V when deployed at J1-18
- If the fault relates to the charge air pressure sensor, check the sensor cable for damage, inspect and replace the sensor if required, and check the fault limits programmed for that sensor
How the code clears
No separate clearing step is listed beyond correcting the underlying cause. Once the obstruction is cleared, the switch is properly mounted, and wiring is confirmed good (with correct 24V signals present at the specified pins), the pot-hole protection mechanism should retract normally and drive speed should return from cutback to normal. For the sensor-related cause, resolving the cable break or short circuit and confirming the sensor operates within its fault limits should clear the fault.
Frequently asked questions
What does fault code 7 mean on a JLG scissor lift?
It means the control system detected that the pot-hole protection mechanism failed to retract while the machine was stowed, so it reduces drive speed to cutback. In a related sensor context, it can also flag a fault at the charge air pressure sensor circuit.
Why is my JLG scissor lift only driving at cutback speed?
If fault code 7 is active, the controller has detected that the pot-hole protection mechanism did not retract properly, and it intentionally limits drive speed as a safety precaution until the issue is resolved.
What are PHP switches and why do they matter?
PHP stands for pot-hole protection, a mechanism on scissor lifts that helps prevent the machine from driving into holes or drop-offs. If the switches monitoring this mechanism don't report correctly, the controller cuts drive speed until it can confirm the mechanism is retracted.
What voltage should I see at the PHP switch wiring?
The left PHP input should read 24V at J1-9 with a 24V output when deployed at J1-10. The right PHP input should read 24V at J1-17 with a 24V output when deployed at J1-18. Missing or incorrect voltage at these points points to a wiring or switch problem.
Can debris cause fault code 7?
Yes. An obstruction around either pot-hole protection mechanism can physically prevent it from retracting, which triggers the fault and the resulting drive cutback.
Is fault code 7 safe to keep operating with?
The machine will still drive, but only at reduced cutback speed, and the underlying protection function may not be working as intended. It should be diagnosed and corrected rather than ignored long term.
Does fault code 7 always relate to the pot-hole protection mechanism?
Not necessarily. The same code number is also documented under a sensor fault group tied to charge air pressure, where the cause is a short circuit or cable break at the sensor. Check both possibilities depending on your machine's symptoms.