Liftmaster 24-51233, BRAKE SOLENOID RELAY
The LiftMaster 24-51233 brake solenoid relay is a service relay used in the industrial brake circuit on select LiftMaster SL3000 commercial slide gate operators. In this type of operator, the brake assembly helps hold the gate when the motor is not driving and releases when the operator is commanded to run. A weak, failed, or incorrect relay can cause a brake that does not release, intermittent movement, humming, nuisance stops, or a gate that feels mechanically locked even though the control board is calling for movement. This is not a general-purpose accessory relay; it belongs in a specific brake control circuit and should be selected by part number, operator model, and wiring diagram. On high-use commercial slide gates, replacing the relay without checking the brake solenoid, wiring, line voltage, and limit/brake timing can leave the original problem unresolved.
Compatible With
- Compatible with LiftMaster SL3000ULE commercial slide gate operators when the parts diagram calls for 24-51233.
- Commonly associated with LiftMaster SL3000UL and SL3000ULE industrial/commercial slide gate brake-control assemblies.
- Used with 2 HP brake solenoid relay applications on select SL3000 operator configurations.
- Verify against the operator nameplate and replacement parts diagram before using on any SL3000, SL3000UL, or SL3000ULE variant.
- Not a universal relay for all LiftMaster slide, swing, or barrier gate operators.
Features & Specifications
| Manufacturer | LiftMaster / Chamberlain Group |
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| Product Type | Brake solenoid relay |
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| Part Number | 24-51233 |
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| Application | Industrial brake solenoid control circuit |
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| Compatible Operator Type | Select commercial slide gate operators |
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| Common Model Reference | SL3000ULE / SL3000UL family |
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| Horsepower Reference | Commonly listed for 2 HP brake relay applications |
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| Notes | Match by parts diagram, relay markings, and wiring layout |
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Also Known As / Related Part Numbers
- 24-51233
- LM-24-51233
- LiftMaster 24-51233
- Brake solenoid relay
- Brake solenoid relay 2HP
- SL3000ULE brake solenoid relay
- Related brake-system reference: K76-51230 brake solenoid, verify separately
- Related SL3000 service reference: 02-51227 stop/reset switch, not a replacement for this relay
Technician Note
If the brake does not release, test the relay as part of the full brake circuit instead of assuming the relay is the only failed item. Check the brake solenoid, wiring terminals, voltage supply, and any heat damage around the brake-control components.
Before Ordering
- Confirm the operator is an SL3000UL or SL3000ULE style unit.
- Match the old relay part number to 24-51233.
- Check the operator parts diagram for the exact brake relay callout.
- Inspect brake solenoid wiring and terminal condition.
- Do not use this as a substitute for unrelated LiftMaster relays.
Important Ordering Warnings
- Part number must match the brake-control diagram.
- Similar relays may have different coil ratings, contact ratings, or terminal layouts.
- A stuck brake can also be caused by a failed solenoid or mechanical brake issue.
- Do not bypass the brake or safety circuit to keep the gate running.
Professional Advisory
Electrical components should be installed and tested by a qualified gate technician. Disconnect power before service and do not bypass safety devices, overload protection, alarms, or manufacturer-required entrapment protection devices.
Product Questions & Answers
What does the LiftMaster 24-51233 relay do?
It controls the brake solenoid circuit on select SL3000 commercial slide gate operators so the brake can release during movement and hold when the operator stops.
Is 24-51233 compatible with every SL3000 operator?
No. It is mainly associated with SL3000UL and SL3000ULE brake-control applications, but the installed model and parts diagram should be checked before ordering.
Can a bad relay make the gate seem locked up?
Yes. If the brake solenoid does not release, the motor may try to run while the brake is still holding. Other brake, wiring, voltage, or control issues can cause similar symptoms.
Is this the same as the brake solenoid?
No. The relay controls the brake solenoid circuit. The brake solenoid assembly is a separate part and should be diagnosed separately.
Should this relay be replaced by a homeowner?
This part is inside a commercial gate operator electrical system. A qualified gate technician should diagnose and replace it safely.
