Key Fob or Thing a Ma Jig

Wednesday, September 7, 2011

Have you bought a key for your vehicle recently?  It can be a bit of a different experience.  Yes, recent developments in ignition keys have produced a great deal of variation in the final product.

The thing you carry around to operate your vehicle can be anything from a normal everyday key to a fob remote control device that does not even require insertion or twisting.

 

If your vehicle has a metal key and the vehicle was made in the 21st century it probably is a transponder type key.  Replacing one of these keys is no longer a one step key cutting process.  As with almost every other device in the world there are electronics involved.

 

This key has to be cut to fit and turn the locks and ignition switch just like any other key  but the look of the key blade might be different.  Some of these keys have internal wavy slots that must be cut on specific key making machines you are not likely to find at the local hardware store.  

 

The electronics of the transponder key are under the hard plastic part that you twist on to turn the lock or switch.  There is no battery in them to wear out.

 

Vehicles that require these transponder keys have theft deterrent systems commonly called immobilizers.  So, not only must your key mechanically match your vehicle to start it but it must also electronically match the immobilizer.

 

How does it all work?  Do you really care?  I will try a simple explanation.  The ignition transponder key electronics are turned on by a switching magnetic field surrounding the ignition lock/switch unit.  When the key is placed in the ignition and the vehicle is turned on the immobilizer computer switches the magnetic field to turn on the transponder key electronics.  The key generates a code that is sent to the immobilizer.  The immobilizer sends out another code to both the key and the the car computer that is in charge of letting the vehicle start (many times the engine control computer).  Both the key and the car computer will do some math on the code number and send the result to the immobilizer.  Both key and car computer should come up with the same answer.  If they are the same, the vehicle is allowed to start.  Simple?  Not!  But effective.

 

So a visit for a new transponder style ignition key also requires a programming procedure be performed on your vehicle.  The key must be matched to the immobilizer and this also requires special equipment and know how. The matching means they are both programmed to do the same math. You are not likely to find either at the local hardware store.

 

This topic came to mind as I myself have been spending more time with my local locksmith lately.  In my business I replace ignition locks and switches as well as every other component on a vehicle.

 

Engine control modules are one of the components that we have to replace now and then.  On some vehicles these modules contain programming that is required to match to the transponder keys and vice versa.

When we replace one of these units, creating the perfect match (a car that starts) requires a trip to my local locksmith.

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