Liftmaster 912B, MAGLOCK CONTROL RELAY
The LiftMaster 912B is a maglock control relay used as an interface between a gate operator control circuit and a magnetic lock or similar access-control load. In many gate systems, the operator logic board should not directly carry the full load of the lock circuit. A relay interface helps isolate the operator command signal from the accessory power circuit so the lock can be controlled in a cleaner, more serviceable way.
This part is most often ordered when a gate operator already has a maglock circuit installed, when a relay has failed, or when a technician is matching an older LiftMaster or Elite commercial gate system to a magnetic lock release. Because maglock wiring can involve separate power supplies, fire access requirements, access-control inputs, and fail-safe behavior, the 912B should be installed from the correct LiftMaster wiring instructions and local code requirements. Do not use this relay to bypass safety devices or create an unsafe gate condition.
Common Replacement Reasons
- Maglock does not release when the gate receives a valid open command.
- Relay contacts are burned, stuck, or no longer switching the lock circuit correctly.
- Existing maglock wiring uses a missing or damaged 912B interface relay.
- Operator board accessory output needs isolation from a lock power circuit.
Compatible With
Common Compatible Applications
- Select LiftMaster commercial gate operators using a maglock interface relay.
- Select Elite commercial gate operators where the parts diagram or wiring diagram calls out model 912B.
- Mega Swing style gate operator applications where the 912B maglock interface is specified.
- 12VDC and 24VDC access-control/maglock circuits when the system design supports this relay.
Additional Systems to Verify
- LiftMaster and Elite swing gate operators with magnetic lock accessories.
- LiftMaster and Elite slide gate operators using a separate maglock release circuit.
- Keypad, card reader, telephone entry, or access-control systems feeding a gate operator lock release circuit.
Important Compatibility Notes
Match the relay voltage, lock power supply, control-board output, and site wiring diagram. A maglock circuit may also need fire department release, emergency access, and code-compliant fail-safe wiring depending on the property.
Features & Specifications
| Feature / Specification | Details |
|---|
| Manufacturer | LiftMaster / Chamberlain Group |
| Product Type | Maglock control relay / access-control interface |
| Part Number | 912B |
| Application | Magnetic lock control interface for gate operator systems |
| Voltage | Commonly associated with 12VDC / 24VDC control applications |
| Compatible Operator Type | Select LiftMaster and Elite commercial gate operators |
| Notes | Use only where the operator wiring diagram or system design calls for a relay interface |
Also Known As / Related Part Numbers
- 912B
- LM-912B
- LiftMaster 912B
- Maglock Interface Board Model 912B
- Maglock Control Relay
Technician Note
When troubleshooting, separate the problem into three areas: the gate operator command, the relay switching action, and the maglock power circuit. Do not jumper out a magnetic lock or safety circuit as a permanent repair.
Before Ordering Checklist
- Confirm the existing part number or wiring diagram calls for 912B.
- Confirm control voltage and maglock power supply voltage.
- Inspect terminal labels and wire locations before removing the old relay.
- Verify the gate still has required monitored safety devices installed and working.
- Use a qualified gate technician if high-voltage power or code-required lock wiring is involved.
Professional Advisory
Maglock and gate-control wiring can affect life-safety access, emergency release, and entrapment protection. Installation should be handled by a qualified gate or access-control technician when the system wiring is not already documented.
Product Questions & Answers
What does the LiftMaster 912B relay do?
The 912B provides a relay interface for controlling a magnetic lock or similar access-control load from a compatible gate operator system.
Is the 912B a safety device?
No. It is a control relay for maglock/access-control wiring. It should not be used to bypass photo eyes, edge sensors, or other required gate safety devices.
Can I use the 912B on any maglock?
Only when the lock power supply, control voltage, and wiring layout match the system design. Verify the operator wiring diagram before ordering.
What symptoms point to a bad maglock relay?
Common symptoms include a maglock that stays locked during a valid open command, relay contacts that no longer switch, or visible damage to the relay terminals.
Should a homeowner install this relay?
A qualified gate or access-control technician is recommended, especially when the installation includes lock power supplies, fire access wiring, or high-voltage operator wiring.
