Fault diagnostic system for vehicles using identification and program codes

• US 5,491,631 A
• Filed: 10/21/1994
• Issued: 02/13/1996
• Est. Priority Date: 12/25/1991
• Status: Expired due to Term

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Iwasa, Seiichi, Mizuno, Kimio, Shirane, Yoshiyuki, Kokubo, Kazuo, Ohno, Tetsuya, Suzuki, Yoshio, Satoh, Takashi, Kuramochi, Kiyoshi
• Primary Examiner(s): Teska, Kevin J.
• Assistant Examiner(s): LOUIS JACQUES, JACQUES H
• Application Number:
  US08/328,341
• Time in Patent Office: 480 Days
• Field of Search: 364/431.01-431.12, 364/424.02, 364/424.03, 364/424.04, 364/550, 364/551.01, 73/116, 73/117.2, 73/117.3, 73/118.1, 123/571, 123/676, 123/568, 123/479, 340/438, 340/439, 340/459, 340/870.09, 340/518, 340/529, 340/825.54, 340/825.52, 395/905, 395/811
• US Class Current: 701/35
• CPC Class Codes: F02D 41/22 Safety or indicating devices for abnormal conditions in air/fuel ratio feedback systems F02D41/1495, in electric control linkage F02D11/107, in purge control systems F02M25/0809
• CPC Class Codes: F02M 26/49 Detecting, diagnosing or indicating an abnormal function of the EGR system
• CPC Class Codes: F02M 26/57 using electronic means, e.g. electromagnetic valves
• CPC Class Codes: G01M 15/05 by combined monitoring of two or more different engine parameters
• CPC Class Codes: Y02T 10/40 Engine management systems
• CPC Class Codes: Y10S 706/905 Vehicle or aerospace
• CPC Class Codes: Y10S 706/911 Nonmedical diagnostics

Abstract

A memory stores a vehicle identifier code which enables identification of a vehicle carrying the same type of electronic control unit (ECU) correspondingly to an ECU identification code (ECU-ID) and display means for displaying the vehicle identifier code is displayed on the basis of the ECU-ID provided by an ECU, and a predetermined fault diagnostic program corresponding to the vehicle identifier code is selected and initiated in response to the input of a verification signal of the displayed vehicle identifier code. When a plurality of faulty parts of a vehicle are detected, a priority table is referred to and fault codes corresponding to the plurality of faulty parts are displayed with priority. The necessary specific work procedure is sequentially displayed according to the selected diagnostic program.

Claims

1. A fault diagnostic system for connection to a computer-aided electronic control unit carried on a vehicle for detecting and diagnosing faults in vehicle parts connected to said electronic control unit, said fault diagnostic system comprising:

means for providing a control unit identification code that identifies the type of electronic control unit that is being carried on the vehicle;

means for providing a vehicle identification code that identifies the type of vehicle on which the electronic control unit is being carried;

storage means for storing a plurality of diagnostic programs;

a priority table in which a fault code and diagnostic priority are assigned for an electronic control unit fault and for each faulty vehicle part respectively;

abnormality detecting means for detecting abnormality of said electronic control unit and vehicle parts and outputting a fault code corresponding to each abnormality;

means responsive to detection of a plurality of abnormalities for accessing said priority table using the plurality of fault codes output from said abnormality detecting means as retrieval keys, and displaying the fault codes corresponding to said abnormalities along with said priority; and

program selecting means jointly responsive to said control unit identification code, to said vehicle identification code, and to a fault code and priority selected by an operator from said display for retrieving one of said diagnostic programs from said storage means for use by said fault diagnostic system.

2. The fault diagnostic system of claim 1 including means for performing a self-diagnostic function for detecting and recording a fault of peripheral equipment connected to said electronic control unit and outputting a fault code, and for communicating with the electronic control unit to diagnose a detected fault of said electronic control unit and peripheral equipment, said fault diagnostic system comprising:

communication control means for performing data communication with said electronic control unit,

first fault code storage means for storing a fault code output from said self-diagnostic means,

self-diagnosis restarting means for restarting said self-diagnostic means in response to storage of said fault code into said first fault code storage means,

second fault code storage means for storing a fault code output from said self-diagnostic means when said self-diagnostic means is restarted, and

means for comparing the contents stored in said first and second fault code storage means to judge that the fault is continuous when said contents stored in said two fault code storage means are coincident with one another, or to judge that the fault is temporary when said stored contents are different from one another.

3. The fault diagnostic system of claim 1 including a self-diagnostic means for detecting and recording a fault of peripheral equipment connected to said electronic control unit and outputting a fault code, and for communicating with the electronic control unit to diagnose a detected fault of said electronic control unit and peripheral equipment, said fault diagnostic system comprising:

communication control means for performing data communication with said electronic control unit,

fault code storage means for storing a fault code output from said self-diagnostic means,

first means responsive to storage of the fault code in said fault code storage means for resetting a fault code recorded in the electronic control unit,

memory means for prestoring a reference value uniquely associated with a given piece of peripheral equipment for use in judging the nature of a fault of said peripheral equipment, and

second means responsive to detection of a peripheral equipment fault by said self-diagnostic means for comparing an output signal of the peripheral equipment with the prestored reference value associated with said peripheral equipment to judge that a fault, represented by the fault code stored in said fault code storage means, is continuous when the output signal of said peripheral equipment is not substantially equal to its prestored reference value, and to judge that the fault is temporary when the output signal off said peripheral equipment is substantially equal to its prestored reference value.

4. The fault diagnostic system of claim 1 including a means for detecting and recording a fault of peripheral equipment connected to said electronic control unit and for displaying a procedure to be used in identifying the source and nature of a detected fault of said electronic control unit and peripheral equipment, said fault diagnostic system comprising:

first storage means for storing therein a plurality of work procedures useful respectively for identifying the source of a detected fault corresponding to a fault code,

second storage means for storing therein a plurality of fault judgment criteria to be used respectively in the performance of each of said work procedures,

first selecting means for selecting from said first storage means a work procedure corresponding to a fault code provided to said fault diagnostic system by data communication from the electronic control unit,

second selecting means for selecting from said second storage means fault judgment criterion corresponding to said selected work procedure for use in the performance of said selected work procedure,

display means for displaying the work procedure selected by the first selecting means, and

means for judging the characteristics of a fault on the basis of said selected fault judgment criterion during the performance of said displayed work procedure to identify the source and nature of a detected fault.

5. The fault diagnostic system of claim 1 including:

means creating an operation state of the vehicle to be checked by providing a known signal input from the external diagnostic system,

means comparing a quantitative measured value, obtained from particular peripheral equipment to be diagnosed in the operation state of the vehicle produced by said known signal input, with a normal value expected to be obtained from said particular peripheral equipment in said operation state, and

means diagnosing that the particular peripheral equipment is faulty when the comparison results in a deviation between said values that exceeds a predetermined amount.

6. The fault diagnostic system of claim 5 wherein said peripheral equipment is an O₂ sensor for detecting an air/fuel ratio in a fuel gas supplied to said vehicle, and the known signal input from the external diagnostic system is a signal for rapidly changing the supplied fuel gas amount in the operation state of the vehicle to be checked, a variation of the O₂ sensor output, responsive to said rapid change known being compared with the expected variation of the O₂ sensor output to perform a fault diagnosis.

7. The fault diagnostic system of claim 6 wherein said signal input increases the supplied fuel gas amount after decreasing it once, and a time duration from the point when the signal for increasing the supplied fuel gas amount is provided to the point when the O₂ sensor output reaches a predetermined reference value is compared with a predetermined reference value of the time duration.

8. The fault diagnostic system of claim 5 wherein said peripheral equipment is an exhaust gas recirculation device for recirculating exhaust gas into the combustion chamber of the vehicle engine consisting of piping communicating between the inlet manifold and outlast manifold of the engine of the vehicle, a valve plug in said piping to control the recirculation amount of the exhaust gas, and an electromagnetic valve for controlling the position of said valve plug, and the known signal input from the external diagnostic system is a signal for opening or closing said electromagnetic valve during stop and operation states of the vehicle engine, respectively, characterized in that

a valve plug position detected in response to each signal for opening and closing the electromagnetic value is compared with a valve plug position expected for each signal for opening or closing the electromagnetic valve, and

a fault diagnosis is performed based upon the result of said comparison.

9. The fault diagnostic system of claim 5 wherein said peripheral equipment is an exhaust gas recirculation device for recirculating exhaust gas into the combustion chamber of the vehicle engine consisting of piping communicating between the inlet manifold and outlet manifold of the engine of the vehicle, a valve plug in said piping to control the recirculation amount of the exhaust gas, and an electromagnetic valve for controlling the position of said valve plug, and the known signal input from the external diagnostic system is a signal for opening or closing said electromagnetic valve during operation states of the vehicle engine, characterized in that

at least one of the times required by the valve plug to open or close in response to the opening and closing signal is compared with the time expected for each signal, and

a fault diagnosis is performed on the basis of said comparison.

10. The fault diagnostic system of claim 5 wherein said peripheral equipment is an EACV device consisting of piping communicating between the upstream and downstream of a throttle valve, and a control valve in said piping, said EACV device controlling the bypass supply fuel amount by means of the control valve thereby to control engine speed when the engine of a vehicle to be checked is idling, and the known signal input from the external diagnostic system is a signal for holding said control valve at various predetermined openings during the idling of the vehicle engine, characterized in that

the engine speeds at said various predetermined openings of said control valve are compared with the engine speeds expected for the individual predetermined openings, and

a fault diagnosis is performed based upon the result of said comparison.