JPH0291451A - Car diagnosis system - Google Patents

Abstract

PURPOSE:To lighten a load on an electronic controller by providing a data correspondence means which transmits data to a car diagnosis device according to call switch-over bit to respective electronic controllers. CONSTITUTION:When correspondence data containing call switch-over bit are transmitted to the network of a car 500 from the data correspondence means of a car diagnosis device 25 through adapter harness 27, respective electronic controllers 501 - 504 receive them. A call switch-over bit of received correspondence data is studied, and it is judged to be for itself or not according to the call switch-over bit. As the result, the called electronic controllers 501 - 504 respond to the car diagnosis device 25, and establish the correspondence relation with the car diagnosis device 25. Thus, troubles diagnosis by organic combination of respective systems can be made possible, and they can continue to execute their own task except a specified electronic controller, and the load on them can be lightened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a vehicle diagnostic system that performs failure diagnosis of a plurality of electronic control devices mounted on a vehicle.

[Prior art and problems to be solved by the invention 1 Conventionally, electronic control units installed in vehicles have used microcomputers to electronically control, for example, the air-fuel ratio. Many of these are equipped with a self-diagnosis function that lights up (or flashes) a self-diagnosis lamp to notify you of the failure if a failure occurs in the sensors or actuators.

However, since it is not easy to determine the extent of the actual failure condition by just lighting (or flashing) the self-diagnosis lamp, at DIP service stations, etc., the output from the electronic control 1L4 version is It is essential to be equipped with a vehicle diagnostic device that can easily check data by displaying it in code, and this vehicle diagnostic device is disclosed in, for example, Japanese Patent Laid-Open No. 12848/1983.

Furthermore, in vehicles in which electronic control devices that perform engine control, transmission control, brake control, cruise control, etc. are mounted as multiple control units, for example, as disclosed in Japanese Patent Application Laid-Open No. 58-26648, In addition, a plurality of control devices are provided with a function of detecting control abnormalities in the control devices themselves and generating abnormal signals, and the generation of abnormal signals from these plural control devices is centrally managed by a central control device. By displaying the details of the abnormality on the display device in response to the occurrence of an abnormal signal, the driver of the vehicle can recognize the details of the abnormality of a specific control device among the multiple control devices installed in the vehicle through a centrally managed display. It is now possible to do so.

However, since the above-mentioned centralized control device only performs failure diagnosis for each control device according to predetermined procedures, if the cause of the failure is related to multiple control devices, an external vehicle diagnostic device can be connected to perform arbitrary control. It is often necessary to read device data and organically diagnose failures. In such a case, it is necessary to connect the connector of the vehicle diagnostic device to the connector of each control device at a service station in the parking lot, etc., to diagnose the failure, which makes the work complicated and difficult to diagnose. The problem was that discovery took time.

For this reason, in-vehicle LANs have recently been constructed by applying so-called local area network (LAN) technology, which connects multiple computers in a relatively small area to multiple electronic control units installed in the vehicle via a transmission network. However, a system has been devised in which an external connection boat is provided in this network to connect the above-mentioned vehicle diagnostic device to perform failure diagnosis.

However, until the vehicle diagnostic device calls a specific electronic control device among the plurality of control devices, establishes a data communication relationship, and executes vehicle diagnosis of the specific electronic control device, a complicated communication procedure is required. Not only does this take time and hinder organic failure diagnosis of each system, but it also places a large load on each of the electronic control devices mentioned above. Control is carried out using
When there is not enough processing time, such as when the engine is running at high speeds, there is a problem in that the original control program cannot be executed normally.

[Object of the Invention] The present invention has been made in view of the above circumstances, and enables any electronic control device mounted on a vehicle to be easily called up by a vehicle diagnostic device, and greatly improves serviceability. It is an object of the present invention to provide a vehicle diagnostic system that can reduce the load on the electronic control device.

[Means for Solving the Problems] A vehicle diagnostic system according to the present invention includes a plurality of electronic control devices mounted on a vehicle and connected via a network, and reads input/output signals of the electronic control devices connected to the network. A vehicle diagnostic system comprising a vehicle diagnostic device for diagnosing a failure by performing a failure diagnosis, wherein the vehicle diagnostic device is provided with a data communication means for providing and transmitting a call switching bit to an electronic control device in the network in a part of the communication data. On the other hand, each of the plurality of electronic control devices is provided with data communication means for determining whether or not the call is to be made in accordance with the call switching bit and transmitting data to the vehicle diagnostic device.

[Operation] With the above configuration, when communication data including the call switching bit is transmitted from the data communication means of the vehicle diagnostic device to the network, this communication data is received by each electronic control device in the network. The received communication data is checked for the call switching bit, and it is determined whether or not it is a coful for itself according to the call switching bit. As a result, the called electronic control device responds to the vehicle diagnostic device and establishes a communication relationship with the vehicle diagnostic device.

[Embodiments of the invention] Hereinafter, the present invention will be described in detail with reference to the drawings.

1 to 5 show a first embodiment of the present invention, and FIG.
1(b) is an external view of a vehicle diagnostic device connected to the vehicle's electronic control device; FIG. 2 is a block diagram of the vehicle's electronic control device and vehicle diagnostic device; The figure is a functional block diagram of the electronic control system, and FIG. 4 is a flowchart, in which (a) is a flowchart showing the communication procedure of the vehicle diagnostic device, (b) is a flowchart showing the communication procedure of the vehicle's electronic control device, FIG. 5 is an explanatory diagram showing the format of communication data.

(Configuration) The reference numeral 500 in the figure represents a vehicle such as a car, and 501 represents an engine control unit comprised of an electronic control unit (ECU) that is mounted on this vehicle 500 and performs air-fuel ratio control, etc.
02 is a transmission control unit consisting of an ECU, 503 is a brake control unit consisting of an ECU that performs anti-lock control, etc., and 504 is an ECU that obtains various information necessary for running the vehicle through arithmetic processing and controls constant speed driving. It is a cruise control unit.

The ECUs 301 to 504 are connected to a power supply BV via a relay RYI that is opened and closed by a key switch 5W10, and include central processing units (CPUs) 501a to 504a, read/write memories (RAMs) 501b to 504b, and read-only memories ( ROM) 501c to 504C and nonvolatile read/write memory (nonvolatile RAM) 501d to
504d, input interfaces 5010 to 5049, and output interfaces 501e to 504e, upper 2 RAMs 501b to 504bk store temporary parameters subjected to various calculations, and nonvolatile RAMs 501d to 504d store Control maps and the like are stored, and the ROMs 501c to 504c store programs, fixed data, and the like.

Then, the ECL 1501 connects the cooling water temperature sensor 9.02 to the sensor 1 via the input interface 501g.
0, suction pipe negative pressure sensor 11, air conditioner switch SW1,
Each signal from the vehicle speed sensor 13, accelerator switch SW5, throttle opening sensor 15, neutral switch SW3, and engine speed sensor 17 is taken in and stored in the ROM described above.
After processing the data according to the program stored in the RAM 501c and once storing it in the RAM 501b, the CPU 501a performs various arithmetic operations based on the stored data. Output interface 501e1 drive circuit 5
Canister barge solenoid 19,E via 01h
Control signals are output to the GR actuator 20, idle control actuator 21, ignition coil 22, injector 23, etc. to perform necessary engine control.

Further, the ECU 302 uses the input interface 502
Each signal of the engine speed sensor 17, vehicle speed sensor 13, accelerator switch SW5, throttle opening sensor 15, and neutral switch SW3 is taken in via Gl,
Output speed change command interface 502e, drive circuit 50
2h to the A/T actuator 525 to perform speed change control according to the operating state.

Further, the ECU 303 uses the input interface 503 described above.
Through Q, brake switch SW6, wheel speed sensor 5
27, performs control calculations for anti-lock according to the control program in the ROM 503c, and sends the control signals to the output interface 503e and the drive circuit 5.
It is output to the ABS brake actuator 528 via 03h to perform anti-lock (anti-skid) control.

Furthermore, the ECU 304 uses the input interface 504 as described above.
The constant speed driving setting switch SW7 and the signals from the vehicle speed sensor 13 are taken in through the output interface 504e.
, the throttle actuator 530 is controlled via the drive circuit 504h to perform constant speed driving control, and the brake switch SW6, accelerator switch SW5, neutral switch SW3, deceleration switch SW8, and resume switch S
When signal No. 8 from each switch of W9 is inputted via the input interface 504q, constant speed running is canceled or constant speed running with acceleration/deceleration is reset.

Further, the ECUs 301 to 504 have their respective input interfaces 5019 to 5040 and output interfaces 501e to 504e connected by a path line 500a to form a network. Pass line 5 above
00a is connected to an external connection connector 24 that constitutes an external connection boat, and to this external connection connector 24,
An input/output connector 26 of the vehicle diagnostic bag @25 is connected via an adapter harness 27.

This vehicle diagnostic device 25 is provided at a dealer's service station, etc., and has a control section 28, a power supply circuit 29, etc. installed inside, and an indicator section 30, a display 31, a keyboard 32, etc. installed outside. It is being

The control unit 28 includes a timer 38 consisting of a CPU 36, a RAM 37, a frequency counter, etc., which are connected to each other via a pass line 35, and an input/output (Ilo>interface 40).
, and a memory cartridge 34h1 that can be freely connected to the outside via a connector 33.

The output signals of the various switches are input to the input side of the 110 interface 40 via the output interfaces 501e to 504e of the ECLIs 501 to 504. Furthermore, the indicator section 30 is connected to the output side of this I10 interface 40, and turns on the various switches mentioned above.

A) By turning on the light emitting diode (LED) DI of the indicator section 30 corresponding to the switch.

D2...I') 10 lights up (or flashes), so that the operation of various switches can be confirmed.

Further, on the input side of the I10 interface 40, a mode selection signal of the keyboard 32 and a mode selection signal of the ECU 30 are connected.
1 to 504 output from the output interfaces 501e to 504e to the drive circuits 501h to 504h.
The control signal and each of the above gt? The output signals of the sensors and the like are input. Further, the output side of this 110 interface 40 is connected to the input interfaces 501o to 504g of the ECLs 1501 to 504 and the display 31.

Further, the memory cartridge 34 can be selectively connected to the programs of the ECLJs 501 to 504, which vary depending on the vehicle model, via the connection connector 33 so that the vehicle diagnostic device body 25a itself determines compatibility. A ROM 41 is provided inside to store diagnostic programs, fixed data, and the like.

Further, the timer 38 is provided with a clock pulse oscillation element 42 that outputs a synchronization signal.

Furthermore, the power supply circuit 29 connected to the control unit 28 is connected to the vehicle 1 (7)ffiIJABVl, :0N10
It is connected via an FF operation switch SW4.

(Functional configuration of electronic control system) Next, the functional configuration of the electronic control system will be explained.

Each of the ECUs 301 to 504 includes calculation means 551a to 551 for processing signals from each sensor and switch.
d, drive circuits 501tl to 504h, which are examples of drive means for outputting drive signals to each actuator, data pickup means 552a to 552d, decoding means 55
3a to 553d, data communication means 554a to 554d
It consists of

The data communication means 554a to 554d are connected to each other by the path line 500a to constitute a network, such as an in-vehicle local area network (L
AN) /, z etc. are formed.

Roughly, the external connection connector 24 is connected to this pass line 500a.

Here, when performing failure diagnosis of the ECUs 301 to 504, the vehicle diagnostic device 25 is connected to the external connection connector 2.
4 and sends communication data from the vehicle diagnostic device 25 to the network, this communication data is transmitted to the network E.
Data communication means 554a to 554 of CU301 to 504
d, and a call switching bit provided in a portion of the communication data is examined.

When the value of the call switching bit is 0, the call switching bit is a global call that informs all ECUs 301 to 504 in the network that the vehicle diagnostic device 25 is calling one of the ECLJs 501 to 504. On the other hand, if the value is 1, the ECU specified by the global call is connected to the vehicle diagnostic device 25.
Indicates a local call that tells you that someone is calling.

The decoding means 553a to 553d interpret the contents of the communication data from the vehicle diagnostic device 25 as W? According to the contents, the data pickup means 552a to 552d are instructed to pick up predetermined data.

The data pickup means 552a to 552d collect various data calculated by the calculation means 551a to 551d,
Alternatively, fixed data etc. stored in the ROMs 501c to 504C are picked up, and the data are transferred from the data communication means 554a to 554d to the path line 5.
Output to 00a.

The vehicle diagnostic device 25 also includes a data communication means 56, a data calculation means 57, a keyboard interpretation means 58, a display driving means 59, a keyboard 32, and a display 31.

With the above configuration, the diagnostic mode etc. manually operated from the keyboard 32 are interpreted by the keyboard interpretation means 58, and the data communication means 56 is transmitted to the path line 5.
Various request signals are output to 00a. At this time, the communication data transmitted from the data communication means 56 first has the call switching bit set to 1, that is, is transmitted as a global call to call the corresponding ECU, and at the same time, the address information of the corresponding ECIJ is transmitted. Ru.

As a result, the data transmitted in response to the corresponding ECtJ of the ECUs 301 to 504 is received by the data communication means 56, calculated by the data calculation first stage 57, and transmitted via the display drive means 59. displayed on the display 31.

(Operation) The communication procedure of the vehicle diagnostic device and the electronic υ control device with the above configuration will be explained based on the flowcharts of FIGS. 4(a) and 4(b).

(Vehicle Diagnostic Device) Before executing the program, the input/output connector 26 of the vehicle diagnostic device 25 is connected to the external connection connector 24 of the vehicle 500, either directly or via the adapter harness 27.

Next, the vehicle diagnostic device 25 is powered on (step 101), and the vehicle diagnostic device 25 is initialized (step 102). Then, data communication means 56 transmits communication data requesting a model code to ECU 301 of vehicle 500. The call switching bit of this communication data is 0, that is, it is output as a global call, and all ECUs 301 to 504 in the network are notified that the vehicle diagnostic device 25 is calling the ECLI 501 (step 103 ). still,
This model code is stored in advance in the ROM 501c of the ECU 301.

Here, the communication data output from the vehicle diagnostic device 25 includes, for example, as shown in FIG. 5, a start bit, address information such as an ECU address, data such as a command, parity check, and so on. Following the call switching bit, a stop bit is sent.

Next, proceed to step 104 and select the corresponding ECLJ.

That is, it is determined whether the ECU 301 has responded and received the model code data that appeared on the pass line 500a. If it is determined that the data can be received, the process advances to step 105; if it is not possible to receive the data, the process returns to step 104 and repeats the determination.

In step 105, the CPU 36 identifies the model and stores the received model code data at a specific address in the RAM 37. Next, the process proceeds to step 106, in which a daple corresponding to the above-mentioned different type code is selected from among the plurality of daples stored in the ROM 41 of the memory cartridge 34.

As a result, a table corresponding to the control unit of the vehicle is identified, and thereafter, diagnosis is executed according to the program stored in this table.

Next, the process proceeds to step 107 and, for example, when diagnosing the cold water temperature data in the ECU 301 based on the output data of the cold water temperature sensor 9, the corresponding mode is input by key operation on the keyboard 32 (for example, (F→0→7→ENT), this mode is read by the CPU 36 of the vehicle diagnosis ff1i device 25 and temporarily stored at a predetermined address in the RAM 37. Thereafter, the diagnostic mode stored in the RAM 37 is called up, and the contents are interpreted by the toeboard interpreting means 58 to select a program corresponding to the diagnostic mode. At the same time, fixed data such as abbreviations and units corresponding to the diagnostic mode are is read out from ROM41 and stored in RAM3.
7 is stored at a predetermined address, and the process proceeds to step 108.

In step 108, the value of the call switching bit is set to O(
For example, address information of the ECU 301 is output from the data communication means 56 to the pass line 500a, and the process proceeds to step 109.

Next, in step 109, the value of the call switching bit is set to 1 (local call), and the diagnostic mode data interpreted by the keyboard interpreting means 58 (for example,
A request for sending the above-mentioned cooling water temperature inside the ECU 301 is transmitted.

In step 110, in response to the local call in step 109, the corresponding ECLJ (for example, E
The data communication means 56 receives communication data output from the CL 1501).

Then, in step 111, this communication data is calculated by the data calculation means 57 and converted into a physical quantity (binary data is converted into decimal and converted into numerical data), and the numerical data is stored in a predetermined address of the RAM 37, and at the same time, The display driving means 59 is provided with the above numerical data and R at step 107.
Fixed data such as abbreviations and units stored in AM37 is output.

Then, in step 112, the display driver 8259
The output signal is outputted to the display 31, and the display 31 displays the numerical value, abbreviation, diagnosis mode number (function number entered by key operation), unit, etc. In the case of the diagnosis mode of the cold n1 water temperature sensor described above, as shown in FIG. 1(b), the abbreviation T for the cooling water temperature is
W, function number F07, numerical value of cooling water temperature data → -14, and unit deqC are displayed. Then, the process returns to step 107 and the next key force is acquired.

Here, when executing a new diagnosis item, for example, the brake control unit (ECU 503) is used as a control unit other than the above-mentioned engine control unit (ECU 501).
), when requesting wheel speed data based on the output signal of the wheel speed sensor 527 in
T and key operation input), the content is interpreted by the keyboard interpretation means 58 as described above, the wheel speed data is received by the data communication means 56 in step 110 through steps 108 and 109, and the data is transmitted in step 111. The calculation means 57 performs calculation and physical quantity conversion (binary data is converted to decimal). Then, in step 112, it is output to the display 31 via the display driving means 59,
The wheel speed data is numerically displayed on the display 31.

As a result, if the vehicle speed data in all ECUs are abnormal, it can be diagnosed that the vehicle speed sensor 13 is faulty, and if only the vehicle speed data in one ECLJ is abnormal, that ECtJ and the vehicle speed sensor 13 are It is possible to detect poor contact between connectors, short circuits, disconnections in wiring, and failures in the ECU, and to organically link each system to conduct comprehensive fault diagnosis.

(Electronic Control Unit) Next, the communication procedure of the ECUs 301 to 504 will be explained.

The communication data from the vehicle diagnostic system @25 is sent in step 2.
01, it is received by each ECIJ 501 to 504 in the network, and the process proceeds to step 202.

In step 202, the call switching bit of the communication data from the vehicle diagnostic device 25 is checked to determine whether or not it is a global call. When the call switching bit is 1, that is, after a global call, the process proceeds to step 203. On the other hand, when the call switching bit is 1, that is, after a local call, the global call in the previous routine causes the vehicle diagnostic system @25 to If not called, exit the routine. However, until the call switching bit of the communication data from the vehicle diagnostic device 25 becomes a global call again, it monitors only the call switching bit, ignores other data, and continues its own task.

In step 203, each ECU 301 to 504 is interrupted, takes in address information, etc. from the received communication data, and determines whether the call is for itself or not. If the above address corresponds to your address, step 2
On the other hand, if the above address does not correspond, the routine is ended and the next data is obtained.

Proceeding to step 204, the ECU called from the vehicle diagnostic device 25, for example, in the case of a model code request to the ECU 301 in step 103 in the flowchart of the communication procedure of the vehicle diagnostic device 25 in FIG. 4(a), The corresponding ECU 301 uses the decoding means 553a to interpret the model code request command sent from the vehicle diagnostic system@25, and sends the data to the data pickup means 552a.
Outputs a request to read the model code.

For example, in the case of a request to send data on the cooling water temperature in the ECU 301 or a request to send wheel speed data in the ECU 303 in step 107 in the flow chart of FIG. The decoding means 553a, 553G decodes the data transmission request from the vehicle diagnostic device 25 as a request for cooling water temperature data or a request for wheel speed data, and sends the cooling water temperature data or wheel speed data to the pig pickup means 552a, 552c. A read request is output, and the process proceeds to step 205.

In step 205, for example, in the case of the above-mentioned model code request, the data pickup means 5 of the above-mentioned ECLJ501
At step 52a, the Ia scale code data previously stored in the ROM 501c is read out, and in response to the request to send the cold N1 water shortage data, the data pickup means 552a of the ECU 301 reads out the cooling water temperature data. In addition, in the request to send the wheel speed data, the E
At the data pickup means 552C of the CU 303, 1
Read out one-wheel trip data.

Then, the process proceeds to step 206 where the C1 data communication means 55
The above model code data via 4a or 554C,
The cooling water temperature data, wheel speed data, etc. are output to the pass line 500a.

As described above, each ECU 301 to 504 only needs to constantly monitor the call switching bit of the communication data from the vehicle diagnostic device 25, and only checks the communication data when the call switching bit becomes a global call. All you have to do is decide whether the call is for yourself or not. Therefore, each time data is transmitted from the vehicle diagnostic device 25,
There is no need to check the data each time to find out whether or not it has been called, and each ECU 301 to 504
load is significantly reduced.

(Second Embodiment) FIG. 6 shows a second embodiment of the present invention, and is an explanatory diagram showing the configuration of an electronic control system. Incidentally, the same parts and months as in the first embodiment are given the same reference numerals, and the explanation thereof will be omitted.

(Configuration) The vehicle diagnostic device 25 and each ECLJ501 to 504 include:
Communication buffers B1 and B2 are provided, and communication data is transmitted and received via these communication buffers Bi and 82. The communication buffer B1. Each of the communication buffers B2 includes registers R1 and R2 and registers R3 and R4, and a flip-flop FF, for example, is connected to the register R4 of the communication buffer B2 of each of the ECUs 301 to 504. This flip-flop FF is operated by the cor switching bit of the communication data transmitted from the vehicle diagnostic device 25, and the CP of each εC'U 301 to 504 is
Output interrupt signals for U501a to 504a,
It constitutes a communication changeover switch that switches communication to the vehicle diagnostic device 25.

(By IJ) Communication data from the vehicle diagnostic device 25 is stored in register R1,
Parallel-to-serial conversion is performed by a communication buffer 81 such as R2, and the signal is transmitted to each ECU 301 to 504. When serial data is transmitted from the vehicle diagnostic device 25, this serial data is received by the communication buffer 82, stored in the shift register R3 in order, and the least significant bit is set in the communication data from the vehicle diagnostic device 25. Contains the call switching bit. Data of a predetermined register length, for example, one word, is stored in the register R3 (shift register).
When the data is stored in the register R4, the data is moved to the register R4 and converted into parallel data.

Here, when the communication data transmitted from the vehicle diagnostic device 25 indicates a global call, that is, when the call switching bit is O, O is input from the shift register R4 to the set terminal S of the flip 70 knob FF. is,
From the output Q to the CPU 501a of each ECU 301 to 504
An interrupt signal (low level) is output to 504a. Then, each ECU 301 to 504 interrupts the task currently being executed, reads the serial-parallel converted data in the communication buffer B2, interprets the contents, and determines whether the call is for itself or not.

At the same time, the output Q of the flip-flop FF is written into the register R5, and information on the interrupt destination is held. still,
To cancel this interrupt and terminate the communication relationship,
Reset data is written to a predetermined position of the register R5 connected to the reset terminal R of the flip-flop FF.

As a result, when the vehicle diagnostic device 25 calls, it takes in the data sent one after another, decodes the contents, and sends the requested data. These procedures are the same as in the first embodiment, and their explanation will be omitted.

On the other hand, when the communication data transmitted from the vehicle diagnostic device 25 indicates a local call, that is, when the call switching bit is 1, the output Q of the flip-flop FF is inverted and the interrupt is canceled. Each ECLI501-504
resumes the running task.

In this second embodiment, each ECU 301 is controlled by a communication switch operated by the call switching bit.
The burden on the software of ~504 is further reduced.

[Effects of the Invention] As explained above, according to the present invention, each electronic control device in the network can automatically control itself according to the call switching bit set in part of the communication data transmitted from the vehicle diagnostic device. Since the corresponding electronic control device responds to the vehicle diagnostic device by determining whether the call is for This not only greatly improves serviceability by making it possible to diagnose faults connected to
Since data transmission to the JFR device is confirmed, devices other than the 11 specific electronic control devices that have confirmed communication with the vehicle diagnostic device mentioned above can continue to execute their own tasks, which has excellent effects such as reducing the load. is played.

[Brief explanation of the drawing]

1 to 5 show a first embodiment of the present invention, FIG. 1 is an explanatory diagram showing a vehicle and a vehicle diagnostic device, (a) is an external view of the vehicle, and (b) is an electronic control of the vehicle. An external view of the vehicle diagnosis 19i device connected to the device, FIG. 2 is a block diagram of the vehicle electronic control device and vehicle diagnostic device, FIG. 3 is a functional block diagram of the electronic control system, and FIG. 4 is a flowchart. a) is a flowchart showing the communication procedure of the vehicle diagnostic device; (b) is a flowchart showing the communication procedure of the electronic control device of the vehicle;
FIG. 5 is an explanatory diagram of the format of communication data, and FIG. 6 is an explanatory diagram showing a second embodiment of the present invention and the configuration of an electronic control system. 25...Vehicle diagnostic device, 500...Vehicle, 501
．． 502, 503.504...Electronic control unit, 56.554a, 554b, 554G, 554d...
Data communication means.

Claims (1)

[Scope of Claims] A plurality of electronic control devices mounted on a vehicle and connected via a network, and a vehicle diagnostic device connected to the network and performing failure diagnosis by reading input/output signals of the electronic control device. In the vehicle diagnostic system, the vehicle diagnostic device includes data communication means for providing and transmitting a call switching bit to electronic control devices in the network as part of the communication data, while each of the plurality of electronic control devices A vehicle diagnostic system comprising: data communication means for determining whether or not a call is to be made according to the call switching bit, and transmitting data to the vehicle diagnostic device.