JPH02163670A - Fault diagnostic device for control unit for automobile - Google Patents

Abstract

PURPOSE:To eliminate a fault diagnostic unit and to easily diagnose the faults of input/output circuit by providing self-diagnostic function on a built-in CPU. CONSTITUTION:A fault diagnostic device is composed of a CPU 2 equipped with a means, with which an output circuit 3 is connected to an input circuit 1 at the time of fault diagnosis and the circuit 1 outputs a fault diagnostic mode to the circuit 3, and a means to execute the collation and decision of a signal inputted to the circuit 1 and setting data. At the time of the fault diagnosis, when the circuit 3 connects the circuit 1 by a connector 8 for diagnosis and a test switch 10 is closed, the CPU 2 goes into the self-diagnostic mode and the setting data is outputted from a setting data output circuit 11 to the circuit 3, inputted through the connector 8 to the circuit 1 and fetched into the CPU 2 again. Next, at every pin of the circuits 1 and 2, data built-in in advance are collated with respective input signals by a deciding circuit 12 and normality or the fault of the circuits 1 and 3 is decided and displayed by turning on a lamp 13 for fault display.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a failure diagnosis device for a control unit for an automobile.

(Prior Art) Conventionally, as this type of failure diagnosis device, there is one disclosed in, for example, Japanese Patent Application Laid-Open No. 177082/1982. As shown in FIG. 5, this device is equipped with a fault diagnosis unit b separate from the automobile control unit a, and this fault diagnosis unit b sequentially changes the input signal to the non-diagnosis side control unit. The output signal is monitored and a failure diagnosis is performed by determining whether or not the output plug is abnormal.

(Problems to be Solved by the Invention) However, the above-mentioned conventional system has the disadvantage of requiring a separate expensive fault diagnosis unit.

The present invention has been made in view of these points, and focuses on the fact that, in particular, in automobile control units, the built-in CPU is often normal, but the input circuit and output circuit are malfunctioning. The object of the present invention is to provide a built-in CPU with a self-diagnosis function, thereby eliminating the need for a failure diagnosis unit and easily diagnosing failures in input circuits and output circuits.

(Means for Solving the Problems) In order to achieve the above object, the present invention outputs setting data stored in the CPU in advance during fault diagnosis, and imports this output data from the output circuit to the CPU via the input circuit.
Internally, it is decided whether the setting data and the input data match or do not match.

In other words, the specific solution of the present invention includes an input circuit and a control signal that generates a control signal according to a signal input to the input circuit.
The present invention is based on a failure diagnosis apparatus for an automobile control unit that includes a PU and an output circuit that outputs a control signal generated by the CPU to the outside.

and a setting data output means for externally connecting the output circuit to the input circuit and outputting setting data to the output circuit when the input circuit receives a fault diagnosis mode signal during fault diagnosis; The CPU is provided with a determining means for determining whether or not the received signal matches the setting data.

(Function) With the above configuration, in the present invention, during fault diagnosis when the output circuit is externally connected to the input circuit, setting data is output from the CPU and then taken into the CPU from the output circuit via the input circuit. In the CPU, the setting data and the input data are compared by the determining means, and if they match, it is diagnosed that the input circuit and the output circuit are normal, and if they do not match, it is diagnosed that one or both of them has failed. Diagnosed.

(Effects of the Invention) As explained above, according to the fault diagnosis device for an automobile control unit of the present invention, the setting data stored in advance and the input data passing through the output circuit and the input circuit of this setting data are compared. Since the built-in CPU is provided with a self-diagnosis function, failures in the input circuit and output circuit can be easily diagnosed without providing a separate failure diagnosis unit.

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

FIG. 1 shows the configuration of an electronic control unit U for an automobile, which is the object of failure diagnosis, at the time of non-diagnosis (normal time). In the figure, various signals detected by an engine rotation speed sensor, an intake air amount sensor, a throttle valve opening sensor, etc. are input into the control unit U.

An input circuit 1 having a large number of input bins, a CPU 2 that creates control signals for the fuel injection amount, the ignition timing of the air-fuel mixture, the in-vehicle air conditioner, etc. based on various signals input to the input circuit 1; It has a built-in output circuit 3 having a large number of output pins for outputting the created control signals to the outside. A connector 4 for signal input is connected to the input circuit 1, and a connector 5 for signal output is connected to the output circuit 3.

Further, an on-vehicle battery 6 is connected as an operating power source.

Next, check the wiring status of the control unit U at the time of failure diagnosis.
As shown in the figure. In other words, when diagnosing a fault, remove the signal input/output connectors 4 and 5, and connect the diagnostic connector 8 to the output circuit 3.
and input circuit 1 are externally connected. At that time, if the number of input pins and the number of output pins are different, as shown in Figures 3 and 4, connect the pins in parallel on the side with more pins to increase the number of pins on the input side and output side. Match.

In addition, in FIG. 2, the test switch 10 is connected to the input circuit 1.
When the test switch 10 is closed, a failure diagnosis mode signal is generated and input to the input circuit 1.

Setting data for failure diagnosis is input into the CPU 2 in advance. The setting data is for setting the output of each pin of the output circuit 3 to 0N10FF. Furthermore, the CPU 2 has a built-in setting data output circuit 11 as a setting data output means, and its function is to place the CPU 2 into a self-diagnosis mode when the input circuit 1 receives a failure diagnosis mode signal from the test switch 10. input to stop the creation of normal control signals, and instead of this, the above setting data is sent to the output circuit 3 sequentially to the first control signal.
It has a function of sequentially outputting from the pin to the n-th pin. Also,
The CPU 2 has a built-in determination circuit 12 as a determination means for determining whether or not the signal input to the input circuit 1 in the self-diagnosis mode matches the setting data. Furthermore, the CPU 2 has a lamp 13 for indicating a failure.
is connected so as to be visible from the outside, and is controlled to be turned on/off by the determination circuit 12.

Therefore, in the above embodiment, at the time of failure diagnosis when the output circuit 3 and the input circuit 1 are externally connected by the diagnostic connector 8,
When the test switch 10 is closed, the CPU 2 enters a self-diagnosis mode. Then, the setting data is outputted from the setting data output circuit 11 to the output circuit 3, and this output signal is inputted to the input circuit 1 via the diagnostic connector 8 and outputted again to the C.
It is taken into PU2.

Then, when input signals are taken in for each bin of the input and output circuits 1 and 3, each input signal and pre-built-in setting data are sequentially compared and determined by the determination circuit 12. the result,
If all terminal pins match, it is considered normal,
If there is a mismatch in any of the terminal bins, it is determined that the input circuit 1, the output circuit 3, or both have failed due to a disconnection or the like, and the failure indicator lamp 13 is controlled to turn on.

In that case, the output of the setting data and the comparison of this setting data with the input signal are performed inside the CPU 2, so the input circuit 1.
The failure of the output circuit 3 can be self-diagnosed by the control unit U itself, eliminating the need for a conventional failure diagnosis unit.

[Brief explanation of the drawing]

Figures 1 to 4 show embodiments of the present invention, with Figure 1 being an internal configuration diagram of the control unit, Figure 2 being an explanatory diagram of the wiring around the control unit during failure diagnosis, and Figure 3 being an illustration of the wiring around the control unit. and the fourth
The figures are explanatory diagrams in which the numbers of pin terminals are different. Fifth
The figure is a wiring diagram for fault diagnosis showing a conventional example. U...Electronic control unit, 1...Input circuit, 2...
- CPU, 3... Output circuit, 10... Test switch (diagnosis mode setting means), 11... Setting data output circuit (setting data output means), 12... Judgment circuit (judging means).

Claims (1)

[Claims] (1) In an automobile control unit comprising an input circuit, a CPU that creates a control signal according to a signal input to the input circuit, and an output circuit that outputs the control signal created by the CPU to the outside, The CPU includes a setting data output means for outputting setting data to the output circuit when the input circuit receives a predetermined fault diagnosis mode signal during fault diagnosis in which the output circuit is externally connected to the input circuit; 1. A failure diagnosis device for a control unit for an automobile, comprising: determining means for determining whether a signal input to an input circuit matches the setting data.