Liftmaster K29-50279, ALARM, Q404
The LiftMaster K29-50279 is a genuine replacement Audible alarm / warning buzzer used in professional gate operator service work. This part is used for replacement audible alarm for select liftmaster commercial gate operators. It is the kind of component that can cause confusing field symptoms when it starts to fail because the operator may still have incoming power, but the control input, reset function, alarm circuit, or protective circuit may not respond correctly. A technician normally checks this part after confirming that the gate is mechanically free, the operator has the correct supply voltage, and the control board is not being held in a fault condition by another device.
Correct fitment matters because LiftMaster and Elite operators often use similar-looking switches, relays, alarms, and electrical accessories with different ratings, wire leads, terminals, or mounting layouts. The safest way to order this item is to match the original part number, the operator model number, and the factory parts diagram. For older commercial gate operators, also check the operator generation, control-box revision, voltage, phase, and any previous board upgrade before assuming that a visually similar part will interchange.
Compatible With
Various LiftMaster commercial gate operators that specify the K29-50279 or Q404 alarm. It is used as an audible alert device for compatible gate operator systems and should be matched by wiring, voltage, mounting, and the operator parts diagram.
Common Compatible Models and Applications
- Select LiftMaster commercial gate operators requiring the Q404 alarm
- Gate operator control panels listing K29-50279
- Commercial gate systems using an OEM audible warning alarm assembly
- Operator alarm circuits where Q404 is the specified service part
Important Compatibility Notes
Some references list this alarm as obsolete or no longer available. Do not disable a required audible alarm. If the alarm is sounding due to entrapment, obstruction, or safety faults, diagnose the system before replacing parts.
Features & Specifications
| Feature / Specification | Details |
|---|
| Manufacturer | LiftMaster |
| Product Type | Audible alarm / warning buzzer |
| Part Number | K29-50279 |
| Application | Replacement audible alarm for select LiftMaster commercial gate operators |
| Compatible Operator Type | Commercial gate, slide gate, swing gate, barrier gate, or access operator applications where this exact part is specified |
| Known Ratings / Reference Details | Q404 |
| Notes | Some references list this alarm as obsolete or no longer available. Do not disable a required audible alarm. If the alarm is sounding due to entrapment, obstruction, or safety faults, diagnose the system before replacing parts. |
Also Known As / Related Part Numbers
- K29-50279
- 29-50279
- Q404
- LM-K29-50279
- LiftMaster alarm Q404
Technician Note
Match this part to the original component and the operator wiring diagram before installation. If the original component failed from heat, water intrusion, repeated overload, shorted wiring, or impact damage, correct that condition before installing the replacement.
Before Ordering
- Confirm the operator model number and product family.
- Match the original part number or parts diagram reference.
- Check voltage, amperage, phase, switch function, connector, and mounting style when applicable.
- Inspect the control box for water damage, burned terminals, loose wiring, or previous non-factory repairs.
- For high-voltage wiring or unsafe gate movement, use a qualified gate technician.
Professional Advisory
Electrical and safety-related gate operator parts should not be bypassed to keep a system running. If the operator has an active alarm, repeated reset condition, overload trip, or damaged wiring, diagnose the cause before returning the gate to service.
Product Questions & Answers
What is K29-50279?
K29-50279 is a LiftMaster replacement audible alarm commonly referenced as Q404 for select commercial gate operators.
Is Q404 the same as K29-50279?
Q404 is the common related reference used for the K29-50279 alarm.
Can I disconnect the alarm if it keeps sounding?
No. Do not bypass or disable an alarm to hide a fault. A sounding alarm can indicate entrapment, obstruction, control, or safety-device issues.
Is this part still available?
Some references list K29-50279 as obsolete or no longer available, so availability should be reviewed before upload or ordering.
Will replacing the alarm fix a fault condition?
Only if the alarm itself has failed. If the operator is generating an alarm because of another issue, the underlying cause must be diagnosed.
