JP2000199732A - Vehicle diagnostic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To check both the electronic control system of a vehicle and the circuit of a body electrical system by using a single vehicle diagnostic apparatus. SOLUTION: A diagnostic mode signal from a keyboard 32, various control signals which are output to the drive circuit of a vehicle from the output interface of an ECU 2 on the vehicle and detection signals from various sensors are input to the input side of an I/O interface at the inside of a vehicle diagnostic apparatus body 25a. In addition, the output side of the I/O interface is connected to the input interface of the ECU 2 and to a display 31. An A/D converter and terminals 45a, 45b for analog signal input are installed on the side of the vehicle diagnostic apparatus body 25a, and the A/D converter is connected to a CPU via a bus line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle diagnostic device having a tester function.

[0002]

2. Description of the Related Art In recent years, an engine mounted on a vehicle electronically controls a fuel injection amount, an ignition timing, an idle speed, and the like, so as to achieve comfortable drivability, purify exhaust gas, save fuel consumption, Improvements in engine output and the like are being made.

[0003] For this reason, if the output signals of various sensors and switches for detecting the engine state or the output signals to various actuators such as injectors are not accurate, it becomes difficult to accurately control the engine, resulting in poor drivability. This leads to worsening, exhaust emissions, worsening of fuel economy, and lowering of engine output.

In recent complicated electronic control systems, even if a failure occurs in a control device, sensors, switches, or actuators, it is difficult to immediately find out the cause of the failure. Japanese Patent Application Laid-Open No. 58-12848 discloses a vehicle diagnostic device that can easily check output signals from various sensors to the electronic control system or signals output from the electronic control device to various actuators. It is essential to equip a so-called hand computer as shown in the gazette.

[0005]

However, the main purpose of the conventional vehicle diagnostic device is to check the input / output signals of the electronic control unit. Therefore, when troubleshooting, check the voltage value of the body electrical system such as various switches and electrometers, whether there is a ground fault, or if there is a disconnection or short circuit in the harness connected to them, use a tester. However, there is a problem that the operation is complicated.

In view of the above circumstances, the present invention has a tester function in addition to a normal diagnostic function for an electronic control system of a vehicle.
It is another object of the present invention to provide a vehicle diagnostic device capable of checking a vehicle electronic control system and a body electrical system circuit together with one vehicle diagnostic device.

[0007]

In order to achieve the above-mentioned object, the present invention has a control unit having a diagnostic function, and is connected to an electronic control unit mounted on a vehicle to input / output the electronic control unit by bidirectional communication. In a vehicle diagnostic device having a tester function while checking signals, an analog signal input terminal for a tester is provided in the vehicle diagnostic device, and the analog signal input terminal is connected to a port connected to a communication line with the electronic control unit. The diagnostic terminal is connected to the control unit of the diagnostic apparatus main body separately and independently via an analog-to-digital converter.

In the vehicle diagnosis apparatus according to the present invention, the failure diagnosis for the electronic control system of the vehicle is performed by reading the data of the input / output signals in the electronic control apparatus into the vehicle diagnosis apparatus through bidirectional communication and checking. In addition, an analog signal input from an analog signal input terminal for a tester provided in the diagnostic device is converted into a digital signal through an analog-to-digital converter, and is separately provided to a port connected to a communication line with the electronic control device. Independently, the data is input to the control unit of the diagnostic device main body.

Therefore, one vehicle diagnostic device is provided with a normal diagnostic function and a tester function for the electronic control system of the vehicle, and when checking the electronic control system of the vehicle and the circuit of the body electric system together, the electronic control system of the vehicle is used. An input / output signal data value in the device and an actual measurement value obtained from an analog signal input terminal via an analog-to-digital converter,
The same device can be used for comparison at the same level.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and FIG.
2A is a schematic side view of the vehicle, FIG. 2B is a front view of the vehicle diagnostic device, FIG. 2C is a front view of main parts of the vehicle diagnostic device showing a display state in the tester mode, and FIG. FIG. 3 is a circuit configuration diagram of the on-board electronic control device and the vehicle diagnostic device, and FIG. 3 is a flowchart showing a diagnostic procedure by the vehicle diagnostic device.

In the figure, reference numeral 1 denotes a vehicle such as an automobile, and 2 denotes an electronic control unit (ECU) mounted on the vehicle 1 for performing engine control and the like.
U) 3, RAM4, ROM5, input interface 6,
And an output interface 7 are connected via a bus line 8.

The input interface 6 includes a water temperature signal TW of the cooling water temperature sensor 9, an air-fuel ratio signal O2 of the O2 sensor 10, a suction pipe negative pressure signal Q of the suction pipe negative pressure sensor 11,
Vehicle speed signal S of vehicle speed sensor 13, throttle opening sensor 1
5, an air conditioner operation signal AC of the air conditioner switch 12, an idle switch 1
Switch signals such as an idle operation signal ID of No. 4 and a neutral operation signal NT of the neutral switch 16 are respectively input.

In the ECU 2, the various signals are transmitted to the RO
Data processing is performed in accordance with the program stored in M5, temporarily stored in RAM 4, and various arithmetic processing is performed in CPU 3 based on the stored data, and output interface 7, Via a drive circuit 18, a canister control device 19, an EGR
Actuator 20, idle control actuator 2
1. Ignition coil 22 and injector 23
And outputs a control signal to control the operation of each actuator.

The ECU 2 has an external connection connector 2.
4 is provided, and this external connection connector 24
An input / output connector 26 provided on a vehicle diagnostic device main body 25 a of the vehicle diagnostic device 25 is connected via an adapter harness 27.

The vehicle diagnostic device 25 is provided at a service station of a dealer or the like. A control unit 28, a power supply circuit 29 and the like are provided inside the vehicle diagnostic device main body 25a, and an indicator unit 30 and a display are provided outside. 31 and a keyboard 32 are provided. Further, a memory cartridge 34 that can be connected from the outside via a connector 33 is connected to the control unit 28.

The control unit 28 includes a CPU 36, a RAM 37, and an I / O connected to each other via a bus line.
An interface 39 is provided. The above CP
The U36 is provided with a clock pulse oscillation element 42 for outputting a synchronization signal.

On the input side of the I / O interface 39, a diagnostic mode signal from the keyboard 32 and the EC
Various control signals output from the output interface 7 of U2 to the drive circuit 18 and detection signals of the various sensors are input. Further, the output side of the I / O interface 39 is connected to the input interface 6 of the ECU 2 and the display 31.

Further, a power supply circuit 29 connected to the control unit 28 is connected to a power supply Vcc of the vehicle via an operation switch 43 and the adapter harness 27.

Further, the memory cartridge 34 can be selectively connected via the connector 33 so that the vehicle diagnostic device main body 25a itself has compatibility with a program of the ECU 2 which differs for each vehicle type. A ROM 41 for storing a diagnostic program and fixed data corresponding to the program of the vehicle type is stored therein, and the control unit 28 of the vehicle diagnostic device main body 25a is stored therein.
And a connector 33 via a bus line 35a.

The memory cartridge 34 has a bus line 35 connected to the control unit 28 of the vehicle diagnostic apparatus main body 25a.
Analog-to-digital converter (A / D) connected via a
An analog signal input terminal 45a, 45b fixed to the memory cartridge 34 is connected to the input side of the A / D 44.

A probe 46 for checking a circuit of the body electrical system is freely connected to the terminals 45a and 45b, and a probe tip 46a is provided at the tip of the probe 46.

When the tester mode is input by operating the keyboard 32 of the vehicle diagnostic device main body 25a, the control unit 28 selectively receives the signal from the A / D 44 and performs various arithmetic processing based on the signal. Do.

Next, the operation procedure of the vehicle diagnostic device 25 will be described with reference to the flowchart of FIG.

A memory cartridge 34 corresponding to the vehicle type is mounted on the vehicle diagnostic device main body 25a, and the input / output connector 26 is connected directly to the external connection connector 24 of the ECU 2 mounted on the vehicle 1 or via an adapter harness 27. After the connection, the operation switch 43 is turned on.

Then, first, at step 102, the vehicle diagnostic device 25 is system-initialized. Then, the routine proceeds to step 103, where the diagnostic mode input by the keyboard 32 is read. That is, the operator inputs and designates the diagnostic mode to be monitored using the keyboard 32 of the vehicle diagnostic apparatus main body 25a. For example, when the operator wants to check the fuel injection panel time, F → 1 → 2 → ENT To check the circuit of the body electric system, enter F → A → 2 → ENT. Then, the RAM 37 of the control unit 28 of the vehicle diagnostic device main body 25a is used.
The specified mode is stored at a predetermined address of the CPU 3.
At 6, the contents are read.

Then, the process proceeds to step 104, where it is determined whether the input mode is the tester mode. If the mode is the normal diagnostic mode, the process proceeds to step 105, and if the mode is the tester mode, the process proceeds to step 109.

First, the case of the normal diagnosis mode will be described. For example, F → 1 → 2 →
If ENT is input and the output of the fuel injection pulse time is specified, the normal diagnostic mode is set, and the routine proceeds to step 105, where the data request signal TX corresponding to this diagnostic mode is set to EC.
Output to U2. Then, in step 106, the above E
Data signal (fuel injection pulse) RX output from CU2
To receive.

Then, in step 107, the received binary data is converted into decimal data by a physical quantity.
Proceeding to step 108, the measured value is displayed on the display 31,
For example, as shown in FIG. 1B, "1.3 msec" is displayed to inform the operator of the fuel injection pulse time.

Next, the case of the tester mode will be described.

For example, in order to check the circuit of the body electrical system on the keyboard 32, F → A → 2 → ENT
Is entered, the tester mode is determined and step 10
9 and the analog signal input terminals 45a, 45
A / D-convert the signal input from b.

Here, the operator operates the terminals 45a and 45b of the memory cartridge 34 connected to the control unit 28.
The probe tip 46a of the probe 46 connected to the terminal is brought into contact with a predetermined terminal of the body electrical system to be measured. Then, the voltage or the like applied to this terminal is changed by the A / D 44 built in the memory cartridge 34 into A
/ D converted and taken into the control unit 28.

Thereafter, in step 107, the measured value is calculated and converted into a physical quantity, and the process proceeds to step 108, where the measured value is displayed on the display 31 as shown in FIG.
"7V" or the like is displayed to inform the operator of the terminal voltage to be measured.

When the terminal voltage is not confirmed, it is possible to predict a disconnection of the harness, a poor grounding, and the like, and check a corresponding portion.

The present invention is not limited to the above-described embodiment. For example, as shown by a dashed line in FIG.
D44, analog signal input terminals 45a, 45b
Is provided on the vehicle diagnostic device main body 25a side, and the A / D4
4 may be connected to the CPU 36 via the bus line 35.

[0036]

As described above, according to the present invention, the input / output signal data value in the on-vehicle electronic control device is the same as the actually measured value obtained from the analog signal input terminal via the analog-to-digital converter. The comparison can be made at the same level with the device. Therefore, the diagnosis operator can quickly and accurately know the failure by comparing the input / output signal data value with the actually measured value and determining the consistency, thereby significantly improving the reliability of diagnosis and the efficiency of the diagnosis operation. .

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention, in which (a)
Is a schematic side view of the vehicle, (b) is a front view of the vehicle diagnostic device,
(C) is a front view of a main part of the vehicle diagnostic device showing a display state in the tester mode,

FIG. 2 is a circuit configuration diagram of a vehicle-mounted control device and a vehicle diagnostic device,

FIG. 3 is a flowchart illustrating a diagnosis procedure performed by the vehicle diagnosis device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... vehicle, 2 ... electronic control apparatus, 25 ... vehicle diagnostic apparatus, 25a ... vehicle diagnostic apparatus main body, 28 ... control part, 34 ... memory cartridge, 44 ... analog-digital converter, 45a, 45b ... analog signal input terminal.

Claims (1)

[Claims] 1. A vehicle diagnostic device having a control unit having a diagnostic function, which is connected to an electronic control device mounted on a vehicle, checks input / output signals of the electronic control device by bidirectional communication, and has a tester function. An analog signal input terminal for a tester is provided in the vehicle diagnostic device, and the analog signal input terminal is separately and independently provided to a port connected to a communication line with the electronic control device via an analog / digital converter. A vehicle diagnostic device connected to a control unit of the diagnostic device body.