FAQs

Buying a replacement remote control can be a little frightening. The employees of Remotes Unlimited understand that because we deal with customers all day every day. We hope that our website provides a clear and logical path for you to confidently select and purchase the replacement part you need. If it doesn't, or you feel more comfortable speaking directly to a member of our staff, please call RUI at 877-719-1900.

• Battery Testing
• Buying Automotive Remote Controls on the Internet
• Buying Keyfobs Elsewhere
• Types of Automotive Remote Controls
• Automotive Remote Technology
• Keyfob Specification Issues
• Automotive Remote Programming Issues
• RUI Practices
• Odd Facts About Remotes

 

Automotive Remote Technology

 

How Does A Remote Work?

A typical current factory keyless entry or aftermarket alarm system includes (1) a "receiver/control module" installed in a vehicle with wires connected to switches for the functions it controls and (2) a "remote transmitter" that sends some form of signal to the receiver, typically using a radio frequency.  The signal is encoded so that, after a "programming" process, a given remote's signal is only relevant to the receiver that has been programmed in a specific vehicle.  (Some systems also include other vehicle components, such as shock sensors.)

The remote itself simply contains a circuit board with some number of buttons and one or two batteries.  When you push a button on the remote, it makes contact with the circuit board, closing a circuit that then causes the transmitter to send a specific coded signal.  If a vehicle's receiver is within range of a transmitter when a button is pressed, the receiver will "hear" the coded signal and try to interpret the signal.  If the transmission is from a remote that was properly programmed to work with a specific receiver, the signal will be understood by the receiver and it will activate the function specified (such as opening or locking the doors or releasing the trunk).

Can Anyone Buy A Remote And Program It To Work With The System In My Vehicle?

Not in most cases.  Programming procedures usually require that a working key be in the ignition.  The requirement that a working key be present is the vehicle owner's security against someone else programming a remote to work with the system in their vehicle.

What Is The Difference Between Fixed-Code And Rolling-Code Transmitters And What Are The Implications?

First generation remotes transmit the same code each time a given button is depressed, hence the term "fixed code".  Radio-frequency signals can be readily captured, stored, copied and re-transmitted; thus, a fixed code remote can be cloned.  This can be a benefit for the consumer because cloning makes it possible to have any number of working remotes for a system.  Also, cloning means that replacement keyfobs can be made by vendors other than the original equipment manufacturer and sold at modest expense (so long as a customer has a working original).  However, the possibility of cloning also creates a perceived security risk.  That is why the current generation of transmitters use coding technology that sends a different code each time a button is depressed, hence the term "rolling code" (aka "code hopping").  There may be many millions or billions of codes among the possible signals transmitted.  The codes are not random; they occur in a pre-determined sequence that is stored in the memory of both the transmitter and the receiver.  When a new remote is synched up with the receiver during the programming procedure, the receiver locates the code being broadcast by the transmitter and then adjusts to accept only a selection of codes that it knows follow the previous code in its stored sequence.  One implication of this is that if you push a button on a rolling code transmitter a very large number of times while it is not near the vehicle, the coded signal then transmitted by the remote will fall outside the range of codes that the receiver treats as acceptable…and the system will have to be re-programmed before it will again accept the transmitter. Some college students with prankster roommates and parents of button-pushing toddlers have already lear ned this fun fact. Another quite intentional implication of rolling code technology is that it effectively protects the proprietary nature of the system's technology, meaning that only the original equipment manufacturer will be able to produce replacement remotes.  That is why some remotes cost several hundred dollars despite the fact that the components and labor to assemble them cost the manufacturer $5 or less.  Don't blame us…call Mercedes, Toyota and the other automobile and alarm manufacturers if you want to complain about this!

What Is A Transponder And How Are They Used In Automotive Security?

According to Wikipedia, one simple general definition of a "transponder" is "…an automatic device that transmits a predetermined message in response to a predefined received signal".  For more than a decade, automobile manufacturers have used transponders in keys as an added passive security feature. Prior to transponder keys (or "chip" keys), a key was a purely mechanical device.  Since most keys are easy to physically copy, these keys offered little actual security.  Transponders establish a coded electronic relationship between a key and an electrical component in the vehicle.  Unless the correct transponder signal is present, the mechanical key is disabled from starting the ignition. More recently, transponders have been used in proximity remotes.  In concert with a push button ignition switch, the transponder in the remote makes use of a key entirely unnecessary (in normal circumstances).  Ironically, proximity remotes often still include a mechanical key for use as a back-up when the primary system fails due to an electrical malfunction.  The most important practical implication of the use of transponders in keys and remotes is that it is another feature that requires a "programming" procedure when a key or remote is being replaced.  And, most important, while many remote transmitters can be programmed by the user, transponder keys typically cannot be.  Thus, keyhead remotes and proximity remotes with an integrated transponder will require use of a scan tool for programming, which generally means a customer will have to take their vehicle and all its associated keys and remotes to a vehicle dealer in order to use a replacement part.