A scissor lift that raises normally but refuses to come down is very different from a machine that will not lift at all.
The successful upward movement already tells you that several parts of the machine are capable of operating.
Depending on the machine design, the lift circuit has been able to:
- Receive a lift command
- Power the hydraulic pump
- Create hydraulic flow
- Extend the lift cylinder
- Raise the scissor mechanism
The troubleshooting question is therefore not simply:
“Why is the hydraulic system not working?”
A better question is:
“What is preventing the machine from releasing or controlling the hydraulic fluid needed for descent?”
This guide explains how to approach a scissor lift that raises normally but will not lower, without immediately replacing the pump, control box or hydraulic components.
Important: Lowering systems and emergency-lowering procedures vary by manufacturer, model and serial number. A raised platform can create serious crushing and stored-energy hazards. Use the correct service manual, safety supports and approved procedures before working beneath or around an elevated scissor structure.
Why a Working Lift Function Is an Important Clue
When the platform raises normally, the machine has already demonstrated that it can create enough hydraulic force to extend the lift cylinder.
That makes some complete failures less likely.
For example, a completely failed hydraulic pump would normally make successful lifting difficult or impossible.
But lowering often uses a different part of the hydraulic and electrical system.
A simplified lifting path may look like:
Lift Command → Pump Motor → Hydraulic Pump → Lift Cylinder → Platform Up
A simplified lowering path may instead look like:
Lower Command → Control Circuit → Descent / Lowering Valve → Controlled Fluid Return → Platform Down
The exact arrangement differs between machines, but the principle is important:
Up and down are not simply the same hydraulic process running in opposite directions.
Many Scissor Lifts Do Not Use the Pump to Power the Platform Down
On many scissor lifts, raising requires the pump to move fluid into the lift circuit.
Lowering may occur by allowing hydraulic fluid to return from the lift cylinder under controlled conditions.
Gravity and the weight of the raised structure can provide the force for descent while a valve controls fluid release.
This means that a machine can:
Raise normally
while still having:
No lowering function.
That is why replacing the hydraulic pump is usually not the first logical step when the platform goes up normally but refuses to come down.
First Confirm What “Won’t Lower” Actually Means
Before diagnosing individual components, define the symptom precisely.
Does the platform:
- Not lower at all?
- Begin lowering and then stop?
- Lower only from one control station?
- Lower only using the emergency-lowering system?
- Lower very slowly?
- Lower intermittently?
- Make a valve or solenoid sound without moving?
These are not the same fault.
The exact behavior helps determine whether the problem is more likely in the command circuit, valve control, hydraulic path or mechanical system.
Compare Platform and Ground Lowering Controls
One of the fastest ways to narrow the fault is to compare the available control stations.
Ask:
Does the platform lower from the ground controls?
If ground lowering works but platform lowering does not, focus more closely on the platform-side command path.
Possible areas may include:
- Platform lower switch or joystick input
- Platform control box
- Platform wiring
- Platform connector
- Control-station selector
If neither station can lower the platform, the fault may be farther downstream in a shared control or hydraulic circuit.
For more on this comparison method, see our Ground Controls Work but Platform Controls Don't Guide .
Check the Lowering Command Before Blaming the Hydraulic System
A hydraulic lowering valve cannot respond if the machine never sends the required command.
Depending on the control system, the lowering request may pass through:
- Joystick or lower switch
- Platform control electronics
- Control wiring
- Machine control logic
- Safety interlocks
- Valve-control output
If the electrical command stops before reaching the lowering valve, replacing the hydraulic valve will not solve the problem.
Does the Machine Recognize the Lower Command?
Look for evidence that the control system is seeing the lowering request.
Depending on the machine, useful clues may include:
- Display or indicator response
- Fault codes
- Audible valve or solenoid operation
- Controller diagnostic information
- Different behavior between control stations
No response at all may point you back toward the command side of the system.
A clear electrical response with no hydraulic movement may shift attention farther downstream.
Check the Control Selector and Emergency Stop Conditions
The selected control station and safety-control state may affect whether the lowering command is accepted.
Inspect:
- Ground / platform selector position
- Emergency stop condition
- Enable controls where applicable
- Related wiring and connectors
A switch can move mechanically while still having an internal electrical problem.
Do not bypass safety circuits as a diagnostic shortcut.
The Lowering Valve Is a Key Part of the Descent Circuit
In many hydraulic lift systems, a valve controls the release of fluid during lowering.
Depending on the design, this may involve:
- An electrically operated solenoid valve
- A hydraulic valve assembly
- A valve integrated into a manifold or power unit
Its role is to control hydraulic fluid leaving the lift cylinder or related circuit.
If the valve does not open when required, the platform may remain elevated even though lifting works normally.
Electrical Valve Command and Hydraulic Valve Movement Are Different Things
A useful diagnostic distinction is:
Was the valve commanded?
versus:
Did the valve actually allow hydraulic flow?
An electrical problem can prevent the valve from being energized.
A hydraulic or mechanical valve problem can prevent proper fluid flow even when the electrical command is present.
This is why technicians should not diagnose the complete valve assembly from one symptom alone.
Check the Solenoid Coil Where Applicable
If the machine uses an electrically operated lowering solenoid, the coil is one part of the valve-control system.
Possible problems can include:
- No electrical supply
- Open coil
- Damaged connector
- Loose wiring
- Incorrect control signal
However, an operating coil does not automatically prove that the hydraulic valve is moving correctly internally.
Electrical and hydraulic operation should be evaluated separately.
A Click Does Not Prove the Valve Is Working Hydraulically
Technicians sometimes hear a click when the lower command is activated and conclude that the valve must be good.
The sound may confirm that something in the solenoid mechanism is moving or being energized.
It does not prove:
- The valve spool is moving through its full travel
- The hydraulic passage is clear
- Fluid is actually returning correctly
- The valve is free from contamination
Continue diagnosing the hydraulic response rather than stopping at the sound.
Hydraulic Contamination Can Affect a Lowering Valve
Hydraulic valves contain relatively small passages and precision moving components.
Contamination can contribute to:
- Restricted movement
- Valve sticking
- Blocked passages
- Abnormal hydraulic response
If valve problems recur or appear after another hydraulic component failure, inspect the fluid and surrounding hydraulic system for contamination.
See our Scissor Lift Hydraulic Contamination Guide for more information.
Check for a Restricted Hydraulic Return Path
Lowering requires hydraulic fluid to move away from the lift cylinder through the designed return path.
A restriction somewhere in that path can slow or stop descent.
Depending on the machine, possible areas may include:
- Valve passages
- Hydraulic hoses
- Fittings
- Manifold passages
- Flow-control components
Do not assume the problem is inside the cylinder simply because the platform is stuck in the raised position.
A Damaged or Incorrect Hose Can Affect Lowering
Hydraulic hoses can sometimes create restrictions without leaking externally.
Possible problems include:
- Kinking
- Internal deterioration
- Crushing
- Incorrect routing
- Incorrect replacement hose
If the lowering problem appeared after recent hydraulic work, review any hoses or fittings that were replaced or disturbed.
Flow-Control Components Affect Descent Speed
Scissor lifts must lower in a controlled manner.
Depending on the design, hydraulic components may regulate the rate at which fluid leaves the lifting circuit.
A problem in this part of the system may cause:
- No descent
- Very slow descent
- Irregular descent
Do not remove or modify flow-control components simply to make the platform come down faster.
Lowering speed is a safety-related machine function and should remain within the manufacturer's specification.
Very Slow Lowering Is Different From No Lowering
A platform that lowers extremely slowly is giving different information from one that does not move at all.
Very slow descent can suggest partial restriction rather than a completely missing command.
Possible areas may include:
- Partially opening valve
- Restricted flow path
- Flow-control problem
- Hydraulic contamination
Measure and evaluate lowering performance according to the manufacturer procedure instead of adjusting the system by feel.
If the Platform Starts Down and Then Stops
A platform that begins lowering and then stops can indicate an intermittent condition rather than a completely blocked circuit.
Look for:
- Intermittent electrical command
- Loose valve connector
- Harness movement
- Valve sticking
- Changing mechanical resistance
Pay attention to whether the problem changes with platform height.
Position-dependent faults can provide valuable diagnostic information.
Mechanical Obstruction Can Prevent Descent
A hydraulic system may be capable of releasing pressure while the structure itself cannot move normally.
Inspect the scissor mechanism for conditions such as:
- Physical obstruction
- Structural damage
- Bent components
- Foreign material in the mechanism
- Abnormal roller or guide condition
Never reach into or work beneath an unsupported elevated scissor structure.
Use approved maintenance supports and procedures.
Look for Problems After Collision or Structural Damage
If the lowering problem began after the machine experienced an impact, inspect the mechanical structure before assuming the fault is purely hydraulic.
A bent or misaligned scissor assembly may require more force to move or may physically bind.
Hydraulic troubleshooting cannot correct a structural problem.
Emergency Lowering Is a Diagnostic Clue—but Not a Repair
Many scissor lifts include an emergency or manual lowering method.
Its design and operation vary by machine.
If the platform can be lowered using the manufacturer's approved emergency-lowering procedure but not through the normal electrical controls, that can provide useful diagnostic information.
It may suggest that the hydraulic circuit is capable of releasing while the normal command or valve-control path requires further investigation.
However:
Emergency lowering should not be used as a permanent substitute for repairing the normal lowering system.
Follow the operator and service manual exactly.
If Emergency Lowering Also Does Not Work
If the manufacturer's approved emergency-lowering method cannot lower the machine, the problem may require closer attention to the hydraulic or mechanical descent path.
Possible areas can include:
- Hydraulic restriction
- Valve or manifold problem
- Mechanical binding
- Machine-specific safety condition
At this point, the machine should remain secured and serviced using the manufacturer procedure.
Do Not Crack Hydraulic Fittings to Make the Platform Come Down
Loosening hydraulic fittings on a raised scissor lift is not an appropriate shortcut for troubleshooting or emergency lowering.
A raised hydraulic system can contain stored energy and pressurized fluid.
Uncontrolled fluid release can cause:
- Unexpected platform movement
- High-pressure fluid exposure
- Equipment damage
- Crushing hazards
Use only the approved lowering and service procedures for the machine.
Do Not Bypass the Lowering Valve or Safety Circuit
Forcing a valve open or bypassing an electrical safety circuit can remove the control that keeps descent predictable.
Lowering circuits are safety-critical.
Diagnosis should determine why the normal system is not operating rather than defeating the system to create movement.
Does the Lower Function Work From One Station Only?
This comparison can significantly narrow the fault.
Ground Lowering Works, Platform Lowering Does Not
Focus more strongly on:
- Platform lower input
- Platform control box
- Platform connector
- Platform wiring
Platform and Ground Lowering Both Fail
Focus more closely on shared areas such as:
- Machine control output
- Lowering-valve circuit
- Valve assembly
- Hydraulic return path
This is another example of using a working function to reduce the number of possible causes.
Does the Pump Motor Run During Lowering?
Do not assume the pump motor should always run while the platform is coming down.
On many systems, lowering occurs through controlled hydraulic release rather than powered pump operation.
Whether motor operation is expected depends on the machine design.
Use the hydraulic schematic and service documentation rather than judging the system by pump sound alone.
Why Replacing the Pump Is Often the Wrong First Move
If the platform raised normally immediately before the lowering fault, the pump has already demonstrated that it can create at least some hydraulic flow.
A new pump will not correct:
- Missing lower command
- Failed lower switch
- Damaged valve wiring
- Failed solenoid coil
- Sticking lowering valve
- Restricted return path
- Mechanical binding
Diagnose the descent circuit before replacing a pump.
Why Replacing the Complete Control Box Can Also Be a Mistake
The lowering input may originate at the platform control box, but the fault can exist farther downstream.
A complete control box replacement will not correct:
- Damaged machine-side wiring
- Failed valve coil
- Hydraulic valve problem
- Restricted hydraulic return
- Mechanical obstruction
Confirm where the lowering command stops before selecting the repair scope.
A Practical Diagnostic Sequence
1. Confirm the exact symptom.
No lowering, slow lowering, intermittent lowering or one control station only?
2. Confirm that lifting operation is normal.
This establishes which parts of the system have already operated successfully.
3. Compare platform and ground lower controls.
Determine whether the fault is station-specific or shared.
4. Confirm the lower command.
Check controls, wiring and machine logic according to the electrical schematic.
5. Check the lowering-valve electrical circuit where applicable.
Separate command problems from valve problems.
6. Evaluate the hydraulic descent path.
Check for valve or return-flow restrictions using the correct service procedure.
7. Inspect the mechanical scissor structure.
Confirm that nothing is preventing normal movement.
8. Verify normal lowering after repair.
Do not consider the machine repaired only because emergency lowering works.
Follow the Descent Path
A useful simplified diagnostic model is:
LOWER COMMAND → ELECTRICAL OUTPUT → LOWERING VALVE → FLUID RETURN → SCISSOR MOVEMENT
Then ask:
At which stage does the expected response disappear?
If there is no lower command, stay on the control side.
If there is a valid valve command but no hydraulic response, move toward the valve and fluid-return circuit.
If hydraulic release occurs but the structure does not move normally, inspect the mechanical system.
This is more effective than replacing parts based only on the fact that the platform is stuck up.
How This Fits Into the Complete Hydraulic System
A scissor lift hydraulic system works as a complete circuit.
The reservoir supplies fluid, the pump creates flow, valves control that flow and the cylinder converts hydraulic energy into movement.
During lowering, the important relationship shifts toward controlled fluid return.
For a broader explanation, see: How a Scissor Lift Hydraulic System Works .
Frequently Asked Questions
Why will my scissor lift go up but not come down?
Possible causes include a missing lower command, platform or ground control problem, damaged wiring, failed valve-control circuit, sticking lowering valve, hydraulic restriction or mechanical obstruction.
Does a scissor lift use the hydraulic pump to lower?
Many scissor lifts lower through controlled release of hydraulic fluid rather than using the pump to force the platform down. The exact design depends on the machine.
Can a bad lowering solenoid keep the platform raised?
Yes, where an electrically controlled solenoid is part of the lowering circuit. However, wiring, control output and the hydraulic valve itself should also be checked before replacing the coil.
Why does the solenoid click but the lift still not lower?
A click does not prove the hydraulic valve is opening correctly. The valve may be restricted, contaminated or mechanically stuck, or another part of the return circuit may be restricted.
Why will my lift lower from ground controls but not platform controls?
That comparison points more strongly toward the platform-side control path, including the lower input, platform control box, connector or wiring.
Can I manually release hydraulic pressure to lower the lift?
Use only the emergency or manual lowering procedure provided by the machine manufacturer. Do not loosen hydraulic fittings or bypass safety circuits to force descent.
Final Thoughts
A scissor lift that raises normally but will not lower should not be diagnosed as a general hydraulic failure.
The working lift function has already given you valuable information.
Focus on the descent path:
Lower Command → Valve Control → Fluid Return → Mechanical Descent
Then determine which stage is missing.
That method helps separate an electrical control fault from a hydraulic valve problem, flow restriction or mechanical issue—and reduces unnecessary parts replacement.
Need Replacement Parts for a Scissor Lift Lowering Problem?
SAIYIS supplies aftermarket AWP replacement parts including control components, switches, wiring parts, hydraulic pumps, motors and related scissor lift components.
Before ordering, confirm the failed component using the appropriate machine service procedure and provide the OEM part number, machine model, serial number and clear photos of the original component.
Visit AWP-PARTS.COM to browse aerial lift replacement parts.
Manufacturer names and OEM part numbers are used for identification and compatibility reference purposes only. Diagnosis and service should follow the appropriate machine documentation.