HomeLink Glossary: Rolling Code, KeeLoq, Security+ Explained

HomeLink manuals throw around rolling code, Security+ 2.0, KeeLoq, and LEARN button without ever defining them. This HomeLink glossary gives you the plain-English meaning of each term you’ll hit programming a gate or garage opener, so you can read a manual, a forum thread, or a service call and know exactly what’s breaking.

For a broader explanation of how the system works end-to-end, see how HomeLink actually works. For the step-by-step programming process with a rolling-code opener, the HomeLink rolling-code programming guide covers each stage in detail.

Fixed code and rolling code

Fixed code is the original remote protocol. Every press of the remote sends the same RF signal — the same bit pattern, every time. Older openers, mostly made before 1994, use fixed code, and some budget models still do. HomeLink can clone a fixed-code remote in a single step: hold the remote near the HomeLink button, press both until the button blinks rapidly, and programming is complete.

Rolling code — sometimes called hopping code — sends a different signal every time the button is pressed. The remote and the opener share a synchronized counter. The opener accepts the next several codes in the expected sequence and ignores everything outside that window. If someone records your signal and replays it, the code is already stale by the time it reaches the opener. Rolling code was introduced broadly in the mid-1990s after researchers demonstrated that fixed-code systems could be captured and replayed.

HomeLink supports rolling code but requires a two-step process: cloning is followed by a training step in which the opener’s LEARN button and the HomeLink button are activated simultaneously to synchronize the counter.

KeeLoq

KeeLoq is a proprietary algorithm developed by Microchip Technology. It is the encryption engine inside most rolling-code systems sold in the US and much of Europe. When you press a rolling-code remote, KeeLoq generates the next code in the sequence using a secret key programmed into the chip at manufacture.

HomeLink, LiftMaster, Chamberlain, Genie, and most other US residential opener brands license KeeLoq. The practical implication: HomeLink can program to any KeeLoq-based opener as long as the frequencies are compatible and the implementation follows the standard. Where programming fails is when a gate opener uses a proprietary encoding that happens to run on a similar frequency but does not use KeeLoq — the signal lands on the receiver, but the opener does not recognize the bit pattern.

Security+ and Security+ 2.0

Security+ is LiftMaster and Chamberlain’s branded name for their first-generation rolling-code system, introduced in the mid-1990s. It uses KeeLoq on a 315 MHz carrier for most US residential models.

Security+ 2.0 is the updated architecture, introduced around 2011. It adds 128-bit AES encryption layered over KeeLoq, encrypted two-way communication between remote and opener, and a bi-directional status confirmation signal. The system also extended effective range and added antenna diversity on the receiver side.

Both versions work with HomeLink. The naming is confusing — Security+ 2.0 is not simply a software increment of Security+. It uses a different communication protocol. When a forum thread says “my opener requires Security+ 2.0,” it means the opener will not pair with first-generation remotes or early HomeLink modules found in some vehicles from the early 2000s.

The physical LEARN button color on LiftMaster and Chamberlain units is the fastest way to identify the protocol: yellow or orange indicates Security+, purple indicates Security+ 2.0, green indicates 390 MHz (typically fixed-code), and red or orange on older units may indicate an earlier proprietary protocol.

The LEARN button

The LEARN button — also called the learning button, the program button, or the smart button depending on the brand — is mounted on the opener’s motor unit or control board. Pressing it once opens a programming window, typically 30 seconds, during which the receiver listens for an incoming remote signal. Present the remote or hold the HomeLink button, and the opener records the code. The programming window then closes automatically.

Location varies. On LiftMaster and Chamberlain garage openers, the LEARN button is usually on the back or side of the motor unit, near the antenna lead. On gate opener control boards, it may be labeled differently and positioned on the PCB itself. The operator manual will specify where it is and what it looks like.

Training button and indicator light

Training button is HomeLink’s name for the small recessed button located near the HomeLink buttons themselves — typically on the visor panel, overhead console, or rear-view mirror housing. On vehicles where rolling-code programming requires returning to the car mid-process, you use this button to re-enter programming mode without erasing what you already stored.

Indicator light is the LED built into each HomeLink button. The blink pattern signals programming status:

• Slow blink: the button is in cloning mode, waiting to receive a remote signal
• Rapid blink: the button has successfully stored a signal
• Steady on: the button is actively transmitting

Some manufacturers describe the pattern as “three slow blinks followed by rapid blinks” as a step confirmation. The exact behavior varies by vehicle model and build year. When the manual description and the actual blink pattern do not match, the vehicle’s owner’s manual takes precedence over aftermarket guides.

Frequencies

HomeLink transmits on several RF bands to cover the range of openers manufactured over the past four decades:

• 288 MHz — a legacy frequency used by some openers from the late 1980s and early 1990s; rarely encountered today
• 310 MHz — used by some gate-specific systems and certain early LiftMaster commercial models
• 315 MHz — the most common US residential frequency for LiftMaster, Chamberlain, Genie, and compatible brands using Security+ or Security+ 2.0
• 390 MHz — found on older LiftMaster and Chamberlain units; often fixed-code
• 418 MHz — used by some Marantec models and certain European-specification openers
• 433 MHz — widespread in Europe; used by most residential gate openers from FAAC, Nice, BFT, and some LiftMaster commercial units; also used by many Asian-market remotes

During the first training step, HomeLink scans these frequencies automatically when you hold a remote near the button. It detects the carrier and locks onto it. The HomeLink frequencies guide covers what each band means in practical terms and which openers use which.

Gate-specific terms: dry contact and single-button control

When forum threads and installation guides discuss connecting an access-control system to a gate opener, two terms appear frequently.

Dry contact describes a simple switch input — two terminals that, when momentarily shorted, trigger an action. Gate openers use dry-contact inputs for open and close commands. The input carries no voltage on its own; an external device — a keypad, a key switch, a loop detector, or an RF receiver — shorts the terminals briefly to send a command.

Single-button control (SBC) is the same concept named from the gate operator’s perspective. SBC input means: short these two terminals for 200–500 milliseconds and the gate moves. Most residential gate operators expose at least one SBC input on their control board, typically labeled “PED” (pedestrian), “OPEN,” or “SBC.”

HomeLink transmits RF. It does not produce a dry-contact signal. For a HomeLink button to open a gate, the gate opener must have an RF receiver that listens for HomeLink’s frequency and encoding, then triggers its SBC input when it receives a valid match. That RF receiver is what comes bundled with a standard gate opener remote kit. If the opener uses a proprietary 433 MHz encoding that HomeLink cannot clone, there is no RF path between HomeLink and the gate.

For more on how the control board receives signals and routes them to the gate mechanism, see how a residential gate opener works.

HomeLink Wireless Control System

The HomeLink Wireless Control System (HLWCS) is an aftermarket accessory made by Gentex — the same company that manufactures built-in HomeLink — for vehicles that do not include HomeLink from the factory. The HLWCS is a small visor-mounted transmitter that programs to openers using the same protocol and frequency range as built-in HomeLink.

Older vehicles, certain base trim packages, and some import models omit HomeLink entirely. The HLWCS adds the functionality without requiring any modification to the vehicle’s interior or wiring. It runs on an internal battery or can be wired to an accessory power circuit. Retail pricing in the US is typically $25–45.

Code synchronization

Rolling-code systems keep a counter in both the remote and the opener. Each button press advances the remote’s counter by one. The opener accepts the next several hundred codes in sequence — this buffer handles normal situations where the button is pressed outside range of the opener. If the remote is pressed many hundreds of times without the opener receiving a signal, the counters can fall too far apart. The opener no longer accepts the remote’s codes.

Resynchronization is straightforward: hold the remote button continuously for several seconds while within range of the opener, or press it several times in quick succession from close range. The opener hears a valid code within its expected sequence, accepts it, and updates its own counter. Normal operation resumes.

The same out-of-sync failure can happen with a HomeLink button after a vehicle battery replacement or after extended storage, since the HomeLink module’s memory is preserved but its counter reference may drift from the opener’s.

Reference

• Gentex Corporation, HomeLink product information: homelink.com
• Chamberlain Group, Security+ 2.0 documentation: chamberlain.com