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SEP 02, 2025

Troubleshooting Your Palfinger ILP Tuck Under Liftgate: Common Problems & Fixes

When your Palfinger ILP tuck under liftgate stops working as expected, getting it back online quickly is critical. This guide walks experienced technicians and fleet operators through common electrical and hydraulic faults using verified diagnostic procedures from Palfinger’s official documentation.

Whether you're dealing with power issues, non-responsive controls, or unusual lift behavior, this article provides step-by-step fault isolation techniques based solely on the Palfinger ILP 25/33 Owner’s Manual. For more general liftgate troubleshooting, read our Guide to Troubleshooting Common Issues.

• Documentation Resources from Palfinger
• Safety First: Electrical Hazards and Authorized Repair
• Liftgate Will Not Power On
• Liftgate Will Not Lower
• Liftgate Will Not Raise
• Electrical and Wiring Checks
• Advanced Diagnosis: Cross Testing Power Circuits
• Common Hydraulic Faults and Fixes
• Conclusion: Partner with Experts for Tough Repairs

Documentation Resources from Palfinger

Information in this article is sourced from Palfinger Tuck Under ILP 25/33 manuals and technical guides as well as our team’s expertise. Always refer to your specific liftgate’s manuals for complete procedures and serial number, model, and year-specific details.

Reference PDFs used:

• Palfinger Interlift ILP Model Owners Manual
• Palfinger Interlift ILP Sales Brochure

Safety First: Electrical Hazards and Authorized Repair

Before beginning any tuck under liftgate diagnostics:

• Always turn off power at the liftgate’s on/off switch.
• Only qualified technicians should perform electrical work.
• Avoid tools or jewelry near batteries to prevent shorts (Owner’s Manual, p. 24).
• Use personal protective equipment (PPE).

Never bypass fuses or install higher-rated components than specified. Doing so risks equipment damage and personal injury (Owner’s Manual, p. 25).

Liftgate Will Not Power On

If your Palfinger ILP tuckaway does not respond at all, start with these checks:

1. Confirm On/Off Switch Is Activated

• For truck installations, the on/off switch is in the cab.
• For trailer applications, it's located at the rear curb-side dock bumper strut (Owner’s Manual, p. 24).

2. Check Circuit Breakers

• Locate the 150A resettable breaker near the vehicle’s main batteries or auxiliary kit.
• If the red reset tab is exposed, push it back in (Owner’s Manual, p. 24–25).

3. Verify Battery Voltage

• Start the vehicle and allow it to run at fast idle to charge.
• Use a voltmeter:
• 12.6V = fully charged (flooded batteries)
• 12.8V = fully charged (AGM batteries) (Owner’s Manual, p. 25)

4. Inspect the 15A In-line Fuse

• Located at the hydraulic power unit solenoid.
• Replace only with the same 15A rating (Owner’s Manual, p. 25).

5. Confirm Ground Connection

• Check that the ground from the hydraulic power unit is secured to a clean chassis ground point (Owner’s Manual, p. 25).

6. Check Oil Level

• Oil must be 1” from the top of the reservoir with the platform down (Owner’s Manual, p. 25).

7. Inspect for Mechanical/Electrical Damage

• Look for damaged wiring, pinched cables, or burned terminals (Owner’s Manual, p. 25).

Liftgate Will Not Lower

If your tuck under liftgate won’t lower, test the control system and valve components:

Diagnostic Steps

• Inspect valves on the cylinders: look for visible damage (Owner’s Manual, p. 26).
• Bypass toggle switch:
• Disconnect black cable #2 from the power unit.
• Disconnect cable #6 from the toggle switch.
• Connect cable #2 to cable #6 directly (Owner’s Manual, p. 26).
• If gate lowers: wiring issue with toggle switch harness or 3-wire harness.
         If gate doesn’t lower:
• Inspect both release valve wires.
• Use voltmeter while holding DOWN function to verify signal voltage.
• If voltage is present, wiring is intact (Owner’s Manual, p. 26).
• Check release valve coil functionality:
• Remove coil cap but leave coil in place.
• Use a screwdriver to test for magnetic pull while DOWN is pressed.
• No pull = defective coil (Owner’s Manual, p. 26).

Liftgate Will Not Raise

If the palfinger tuck under liftgate fails to lift:

Step-by-Step

• Check lift cylinder valves: look for visible damage (Owner’s Manual, p. 27).
• Bypass solenoid:
• Jump cable #2 to small solenoid terminal.
• Caution: stand clear—gate will rise if solenoid is working (Owner’s Manual, p. 27).
• If gate raises: wiring to toggle or 3-wire harness is faulty (Owner’s Manual, p. 27).
• If gate does not raise:
• Listen for solenoid click:
• No click: Solenoid or thermo switch is faulty.
• Click present: Use voltmeter to check voltage at large motor studs (Owner’s Manual, p. 27).
• If voltage is present: Motor is likely failed internally (bad brushes or windings).
• If no voltage at motor: Bad connection at solenoid or internal solenoid failure (Owner’s Manual, p. 27).

Electrical and Wiring Checks

Electrical faults in the tuck under systems often trace back to simple wiring or grounding issues.

Key Components to Inspect

• 150A circuit breakers: Verify reset state and amperage match (Owner’s Manual, p. 28).
• Fuse safety: Never bypass with metal tools or incorrect fuse ratings (Owner’s Manual, p. 28).
• Auxiliary batteries: Must be properly grounded to the vehicle chassis (Owner’s Manual, p. 28).

Wiring Diagrams

Refer to:

• p. 30–31 for truck and trailer wiring
• Gravity down vs. power down configurations
• Toggle switch and solenoid wiring layout (Owner’s Manual, p. 30–31)

Use diagrams to trace current flow and ensure proper installation per configuration.

Advanced Diagnosis: Cross Testing Power Circuits

When trailer-mounted ILP liftgates are not charging or behaving intermittently, cross-testing ensures all connections are functional.

Use a Battery Load Tester to Test Power Path (Owner’s Manual, p. 29):

Tractor Test

• Ground: Tractor chassis
• Positive: Single pole coil cord plug
• Load test the full tractor circuit

This installation flexibility makes the ILP Pallet Pro series suitable for mixed-use fleets and varied body styles.

Trailer Test

• Ground: Trailer chassis
• Positive: Plug receptacle on trailer
• Load test entire trailer power and ground loop

Full System Test (Tractor + Trailer Together)

• Ground: Tractor chassis
• Positive: Trailer plug receptacle
• Confirms through-path from tractor batteries to liftgate components (Owner’s Manual, p. 29)

Note: Low voltage tests will not uncover weak ground connections—use full-load testing only.

Common Hydraulic Faults and Fixes

Certain platform issues—like uneven lowering, weak lifting, or jerky movements—may point to hydraulic problems rather than electrical ones. Understanding how the system is designed to operate can guide better diagnostics.

Gravity Down Systems

• Lowering relies on gravity plus release valves (S1/S2) (Owner’s Manual, p. 32).
• Each lift cylinder has:
• Release valves (S1, S2): Energized to allow fluid return during lowering.
• Flow restrictors (R1, R2): Control descent speed.
• Fault symptoms:
• Platform won’t lower = Valve coil issue or mechanical blockage.
• Uneven or jerky descent = Clogged flow restrictors or air in lines.

Power Down Systems

• Lowering is powered via motor and additional shift valve (S5) (Owner’s Manual, p. 33).
• System uses:
• S1/S2 + S5 for controlled down movement.
• Fault symptoms:
• No lowering = Motor, S5 valve, or wiring failure.
• Slow or hesitant lowering = Valve not fully shifting or low fluid pressure.

Key Diagnostic Tips:

• Always verify fluid level and condition before assuming component failure (Owner’s Manual, p. 25).
• Remove and inspect valve coils for magnetic pull response.
• If suspecting flow restriction, check for:
• Debris in ports
• Damaged internal seals
• Air trapped in hydraulic lines (Owner’s Manual, p. 32–33)

Conclusion: Partner with Experts for Tough Repairs

This guide covers key issues that may arise in your tuck under liftgate, including complete power loss, failure to lift/lower, hydraulic irregularities, and system-wide circuit diagnostics. Following each step carefully will help isolate faults quickly and get your equipment back in service.

For help sourcing OEM replacement parts, contact our team at LiftGateMe.