Transponder keys can also be called “chip keys”. Transponder keys are ignition keys with signal-emitting chips built inside.
The key is designed with a long shaft with a small black module within that shaft. For the key to operate properly the module has to have contact with both sides of the key. The head of the key emits a radio frequency from the chip that should match the pre-programmed code of the ignition. That way the car will only respond to the key programmed for it. Many cars immobilize if the wrong key is used by intruders. Chip Keys  successfully protect cars from theft in this way. This is why chip keys are so popular in modern cars and are helping decrease car theft worldwide.
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The key is operated by the user simply inserting it into the ignition. This allows one of the resistors to complete the simple circuit which will in turn involve the three other resistors.
This is where the security of the key kicks in. If the value of the resistor is wrong, or the key is a normal key without a resistor, the circuit of the car’s electrical system will not allow the car to be turned on.
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