LiftMaster 33LM 390 MHz Garage Door Remote Transmitter
The LiftMaster 33LM is a legacy 390 MHz three-button remote transmitter used mainly where an older commercial door, gated access, or external receiver installation needs separate open, close, and stop commands. Unlike a typical single-button residential transmitter that cycles the opener through one step-by-step command, the 33LM style remote is tied to older three-button control arrangements. It is commonly searched for older DIP-switch or fixed-code radio systems, especially when the existing receiver was installed to mimic a wall station with separate commands. Because radio control technology changed over time, customers should not assume that a 390 MHz remote will work just because the opener says LiftMaster. The receiver model, DIP-switch format, number of channels, and control wiring must all match the application.
Compatible With
- Select LiftMaster 390 MHz fixed-code / DIP-switch receiver applications
- Older Chamberlain and Sears Craftsman 390 MHz compatible receiver systems when the code format matches
- Commercial door operator installations using separate open, close, and stop radio commands
- Three-button radio control setups using compatible multi-channel receivers
- Legacy systems where 33LM is listed in the original accessory or receiver instructions
- Modern replacement path may include 813LMX where the receiver/application supports it
Features & Specifications
| Manufacturer | LiftMaster / Chamberlain |
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| Product Type | 3-button remote transmitter |
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| Part Number | 33LM |
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| Application | Legacy open-close-stop radio control |
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| Frequency | 390 MHz |
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| Code Type | Older fixed-code / DIP-switch style applications |
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| Buttons | 3 |
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| Common Button Use | Open, close, stop |
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| Notes | Match receiver model and coding style before ordering |
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Also Known As / Related Part Numbers
- 33LM
- LiftMaster 33LM
- LM-33LM
- 33LMC related Canadian reference
- 813LMX related replacement path
- 813LM related commercial DIP remote family
- LiftMaster 390 MHz open close stop remote
- LiftMaster three-button 390 MHz remote
Technician Note
The 33LM should be matched to the receiver, not just the operator brand. Many operators can accept external receivers, and the radio compatibility depends on the installed receiver's frequency and code technology.
Before Ordering Checklist
- Confirm the receiver operates on 390 MHz
- Confirm the system uses older fixed-code or DIP-switch style programming
- Confirm the application needs three separate commands, not a one-button toggle remote
- Check whether 813LMX is being used as the current replacement path
- Verify the installed receiver and operator wiring before replacing multiple remotes
Professional Advisory
Commercial open-close-stop control should be installed so the stop command and required safety devices operate correctly. Do not bypass wall stations, safety sensors, or entrapment protection to make a remote work.
Important Ordering Warnings
- Not for yellow learn button Security+ 2.0 residential openers
- Not for 315 MHz-only systems unless using a replacement remote designed for that frequency
- Not a rolling-code residential remote
Questions & Answers
Is the 33LM a 390 MHz remote?
Yes. The 33LM is commonly associated with 390 MHz legacy LiftMaster radio control applications.
Does the 33LM work like a normal one-button garage remote?
No. It is a three-button remote normally used for open, close, and stop style control.
Can the 813LMX replace a 33LM?
In many legacy commercial applications, 813LMX is used as a replacement path, but the receiver and coding style must be verified.
Will this work with a yellow learn button opener?
No. Yellow learn button openers use Security+ 2.0 technology and generally require different accessories.
What should I check before ordering a 33LM?
Check receiver model, frequency, coding method, and whether the operator is wired for three-button open-close-stop control.
