Immobilizer for preventing unauthorized starting of a motor vehicle and method for operating the same
First Claim
1. An immobilizer for a motor vehicle, comprising:
- a common data line;
motor vehicle control devices each having an identification code word and each being connected to said common data line; and
at least one motor vehicle test unit having desired code words identifying said control devices;
said at least one test unit being connected through said common data line to said control devices;
said at least one test unit transmitting a request signal, at least during every engine starting operation, through said data line to all of said control devices, causing said control devices to transmit back their identification code words;
said at least one test unit comparing the identification code words being sent back with the desired code words and determining how many of said control devices reply with a correct identification code word;
said at least one test unit disabling at least one of said control devices, for preventing starting and driving of the motor vehicle if fewer than a prescribed number of said control devices reply with their identification code word in the event of an interrogation for the identification code words;
and said at least one test unit enabling all of said control devices if at least the prescribed number of said control devices reply with their identification code word in the event of the interrogation.
2 Assignments
0 Petitions
Accused Products
Abstract
An immobilizer for a motor vehicle and a method for operating the immobilizer include a test unit, control devices connected through a data line to the test unit, and at least one ignition key having a transponder. When the ignition key is actuated, the test unit transmits a request signal through the data line to all of the control devices, which respond thereto by transmitting back identification codes which are compared with desired codes. The test unit prevents starting of the motor if fewer than a prescribed number of control devices reply with their identification code. The test unit enables all of the control devices if at least the prescribed number of control devices reply with their identification code word, in the event of interrogation.
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Citations
20 Claims
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1. An immobilizer for a motor vehicle, comprising:
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a common data line; motor vehicle control devices each having an identification code word and each being connected to said common data line; and at least one motor vehicle test unit having desired code words identifying said control devices; said at least one test unit being connected through said common data line to said control devices; said at least one test unit transmitting a request signal, at least during every engine starting operation, through said data line to all of said control devices, causing said control devices to transmit back their identification code words; said at least one test unit comparing the identification code words being sent back with the desired code words and determining how many of said control devices reply with a correct identification code word; said at least one test unit disabling at least one of said control devices, for preventing starting and driving of the motor vehicle if fewer than a prescribed number of said control devices reply with their identification code word in the event of an interrogation for the identification code words; and said at least one test unit enabling all of said control devices if at least the prescribed number of said control devices reply with their identification code word in the event of the interrogation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for operating an immobilizer for a motor vehicle, which comprises:
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during each engine start operation of a motor vehicle, transmitting a user code word to a test unit of the motor vehicle and verifying the user code word in the test unit; transmitting a request signal from the test unit through a data line to all of a given number of control devices, at least during every engine starting operation, causing the given number of control devices to transmit back identification code words; comparing the identification code words being sent back with the desired code words, in the test unit; disabling at least one of the control devices, with the test unit, for preventing starting and driving of the motor vehicle if fewer than a the prescribed number of the control devices reply with their identification code word in the event of an interrogation for the identification code words; and enabling all of the control devices, with the test unit, if at least the prescribed number of control devices reply with their identification code word, in the event of the interrogation. - View Dependent Claims (17, 18, 19, 20)
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Specification