Method for operating a vehicle security system including code comparison after starting which counts start attempts

• US 5,703,413 A
• Filed: 12/10/1996
• Issued: 12/30/1997
• Est. Priority Date: 01/16/1996
• Status: Expired due to Term

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Treharne, William David
• Primary Examiner(s): Elms, Richard T.
• Application Number:
  US08/763,026
• Time in Patent Office: 385 Days
• Field of Search: 307/9.1-10.6, 180/287, 340/425.5, 340/426, 340/825.3, 340/825.32, 340/825.34, 340/825.44, 340/825.69, 340/825.72, 364/423.098, 364/424.045, 364/424.034
• US Class Current: 307/10.5
• CPC Class Codes: B60R 25/04 operating on the propulsion system, e.g. engine or drive motor
• CPC Class Codes: B60R 25/24 using electronic identifiers containing a code not memorised by the user

Abstract

A security system for an automotive vehicle having an engine is operatively connected between engine running electrical components that are connected to an electrical power source and a lock switch having at least two operative positions. The security system has a key with a memory device carried thereon with a first security code stored in the memory device. A theft control module having a memory storing a second security code is operatively connected between the switch and the engine running electrical devices. The theft control module operates to first permit the engine running electrical components to enable the starting of the engine and then to compare the first and second security codes. Before starting the engine, a counter is compared to a predetermined number so that the engine starting is limited to only a predetermined number of attempts. The engine is disabled if the number of attempts exceeds the predetermined number. An engine controller further transmits a challenge code to the theft control module which calculates a response code based on a secret algorithm which is sent to and compared to a calculated comparison code using the algorithm by the engine controller.

Claims

1. A method for operating a security system for an automotive vehicle having an engine including engine running electrical components and an electronic engine controller, said automotive vehicle including a lock switch having a selected position providing power to said engine running electrical components to run said engine, said lock switch being movable by a key having a predetermined cut, said key further containing a first security code stored electronically, said electronic engine controller comprising a counter for counting an attempted start count, said security system having a theft control module operatively connected between said electronic engine controller and said lock switch, said theft control module having a memory storing a second security code and having means for communicating with said key to retrieve said first security code, said method comprising the steps of:

using said key to place said lock switch in said selected position;

comparing said attempted start count to a predetermined number;

disabling said engine from running if said attempted start count exceeds said predetermined number, otherwise enabling starting of said engine;

incrementing said attempted start count;

operating said theft control module to interrogate said key for said first security code;

receiving said first security code into said theft control module;

comparing said first security code with said second security code;

if said first security code does not equal said second security code, then disabling said power to said running electrical components and setting said attempted start count to be greater than or equal to said predetermined number;

if said first security code equals said second security code, then;

signaling said electronic engine controller of said equality;

generating a challenge code in said electronic engine controller;

transmitting said challenge code to said theft control module;

calculating a response code in said theft control module based on a secret algorithm operating on said challenge code;

transmitting said response code to said electronic engine controller;

receiving said response code in said electronic engine controller;

calculating a comparison code in said electronic engine controller based on said secret algorithm;

comparing said response code to said comparison code;

if said comparison code equals said response code then resetting said attempted start count and supplying power to said engine running electrical components;

if said comparison code does not equal said response code then disabling said power to said running electrical components and setting said attempted start count to be greater than or equal to said predetermined number; and

if no response code is received within a predetermined time then disabling said power to said running electrical components.