Understanding Transponder Key Systems

By Greg Jessop, Pop-A-Lock

The transponder key contains an electronic micro-chip built into the head of the key, which is why some people call them chip keys. Transponder is short for transmitter and responder. The basic purpose of transponder key systems is to eliminate auto theft, and therefore it is central to your car’s security system, or anti-theft system. Due to the high number of stolen Corvettes, GM was the first US auto manufacturer to introduce a chip key on the 1985 Corvette. Corvette thefts dramatically decreased as a result of the VATS key and system – Vehicle Anti-Theft System (VATS).

Today’s automotive transponder system consists of the electronic chip key, the antenna ring (induction coil) around your ignition, your car’s computer (ECM – Engine Control Module), and the immobilizer. Once a programmed key is inserted into the ignition lock cylinder and turned to the ON position, the antenna ring sends out a burst of energy through radio frequency. The transponder chip will absorb that energy and send back a radio frequency signal, the identification code, to the antenna ring. The antenna ring sends that ID code to the car’s computer. If the ID code from the key matches the ID code in the computer’s memory, the immobilizer is disabled and the vehicle will start. The car’s security light will go out once the key has been recognized. If the security light blinks, that means the car’s computer isn’t recognizing the ID code from the chip key and the car won’t start. In that event, the typical solution is to call a Locksmith like Pop-A-Lock to cut and program a new transponder key.

In the following sections, I will give a general overview of anti-theft systems and the evolution of transponder key systems by manufacturer.

Ford / Lincoln / Mercury:

Ford introduced their Passive Anti-Theft System (P.A.T.S.) in 1996 and shortly thereafter rolled it out on the Crown Victoria, Expedition, Explorer, F150, Mustang, Ranger, Taurus, Windstar, Cougar, Grand Marquis, Mountaineer, Mystique, Sable, Continental, Mark 8, Navigator, and Town Car. Today, most Ford, Lincoln, Mercury brand cars contain an anti-theft system and will require a programmed transponder key to start the car. If a transponder key has been lost or stolen and the customer is concerned about theft, Pop-A-Lock can “clear / erase” the PATS ID code stored in the car’s computer memory so that lost or stolen key will no longer work. Our programming machine can create a new PATS ID code and we can program a new key to match that new ID code. In this way, only the new key will start the car, not the lost / stolen key.

In 2006, Ford came out with the remote head key, or remote key, whereby the keyless entry remote is built into the head of the key. The key blade is a standard Ford 8 cut and there are either 3 or 4 buttons on the remote. Standard cut remote head keys are available on the 2007–2014 Edge, 2007–2012 Escape, 2009-2015 Expedition, 2007-2015 Explorer, 2011-2015 F150, 2007-2014 Flex, 2008-2011 Focus, 2006-2012 Fusion, 2010-2014 Mustang, 2007-2014 Taurus, 2007-2009 MKS, 2007-2012 MKX, 2007-2013 MKZ, 2011-2014 Navigator, 2006-2009 Zephyr, 2007-2011 Mariner, 2007-2011 Milan, and the 2008-2009 Sable. These remote keys are about $100 more expensive than a basic chip key without the push buttons. A basic transponder key will also work in these vehicles. We at Pop-A-Lock carry these remote head keys and can cut and program them from our vans at your location.

Ford Motor Company advanced their key technology with their introduction of the high security, laser cut key in 2009. The metal blade is cut to code in 3 dimensions (depth, length, and width) giving it a “laser-cut” look to the blade. These high security, laser cut, remote head keys are included on the 2012-2015 Escape and Focus, 2009-2013 Taurus, 2014-2015 Transit, 2013-2015 C-Max, and the 2010-2012 MKS. Since the machine needed to cut a laser cut key is pretty expensive, not many locksmiths own that machine. We at Pop-A-Lock have a laser key cutter and are able to cut and program these high security remote head keys at your location. We carry both the high security transponder key, as well as the high security remote head key with 4 buttons (lock/unlock/panic/trunk).

Finally, in 2011, Ford introduced the Proximity System on certain vehicles. This “smart” key is a proximity remote FOB. To start the car, the user simply pushes the start button on the dashboard while depressing the brake pedal. The vehicle will start because the antenna ring has detected the ID Code programmed into the smart key FOB. Since the FOB runs on a battery as opposed to a transponder key, the antenna ring can detect the radio frequency signal at a much wider range. The Proximity FOB includes an emergency metal insert key that allows you to unlock the car in case the battery dies. Ford and Lincoln vehicles that offer a proximity FOB system are the 2011-2014 Edge, 2011-2014 Flex, 2012-2014 Focus, 2013-2014 Taurus, 2013-2014 MKS, 2011-2014 MKX, and the 2013-2014 MKZ. Since we don’t get many car key replacement requests for these vehicles since they are newer, we do not have these in stock but can get them next day and can program it at your location as well as cut the insert key.

General Motors (Buick, Cadillac, Chevrolet, GMC, Oldsmobile, Pontiac, and Saturn):

As mentioned above, GM was the first domestic OEM to incorporate a chip key system on the 1985 Corvette in order to dramatically reduce Corvette thefts. This VATS system was a rudimentary system, compared to today’s transponder technology, whereby the VATS value of the key must match the VATS value stored in the car’s computer memory in order for the car to start. VATs only had values from 1 to 15. We at Pop-A-Lock Locksmith carry all VATS keys, both double sided and single sided, and can interrogate the vehicle to determine the correct VATS value. We do all of this on site at your location.

In addition to VATS, GM came out with other anti-theft systems such as MATS and PASSLOCK. MATS, Mechanical Anti-Theft System, introduced in 1992, is simply a design change on the ignition lock cylinder that makes it much more difficult to forcibly turn the plug and start the car without a key. PASSLOCK, introduced in 1995, contains a sensor built into the ignition cylinder. It operates on one of ten electromagnetic values which is also stored in the car’s computer memory. Any attempt to force-rotate the ignition lock cylinder will damage the magnet sensor and immobilize the vehicle. We have replaced many MATS and PASSLOCK ignitions for customers as they have called about stuck keys, or keys that won’t turn in these ignitions.

Today, the most common transponder keys for GM vehicles are the Circle Plus keys and the PK3 (PASSKey3) keys. These are standard, 10 cut keys that operate the door and the ignition.

In 2010, GM introduced the Flip Remote Key. This is a high security, laser cut metal key that “flips” out of the FOB like a switch blade. Depending on your car’s trim package, the FOB may or may not be a Proximity key whereby you push a button to start the car. The push-to-start feature is called the E-Z Passive System (E-Z Key). The E-Z Key, aka Flip Remote Key is available on the 2010 -2014 Buick LaCrosse, 2011-2014 Buick Regal, 2012-2014 Buick Verano, 2010-2014 Chevy Camaro, 2010-2014 Chevy Cruze, 2010-2014 Chevy Equinox, 2012-2014 Chevy Sonic, 2011-2014 Chevy Volt, and the 2010-2014 GMC Terrain.

Some Cadillac models such as the 2008-2014 CTS, 2007-2014 SRX, 2005-2013 STS, and the 2008-2009 XLR have a proximity remote FOB system whereby the vehicle starts by pressing the start button on the dash board. The same FOB acts as the transponder proximity key and the remote but the car will not start unless the antenna ring detects the correct ID Code in the transmitter. The 2005-2014 Chevy Corvette has this system as well.

We at Pop-A-Lock Locksmith can cut and program all GM transponder keys, metal keys, Flip Remote Keys, and Proximity Smart Key FOBs on the spot at your location.

Next week I will review transponder key systems for Chrysler, Dodge, and Jeep.