On-vehicle electronic control unit

The invention provides an on-vehicle electronic control unit wherein all types of combinations of electrical equipment can be controlled by the electronic control unit with a common arrangement without changing the arrangement of the microcomputer, the print circuit board or the like, which makes it possible to reduce the number of parts of the on-vehicle electronic control unit to a large extent and reduce the cost thereof. The memory portion of a microcomputer of the electronic control unit stores the control programs for all types of electrical equipment to be controlled. Input terminals are opened and/or ground in accordance with the combination of electrical equipment to be controlled so that the microcomputer can recognize the type of the control program to read from the memory portion. In this manner, the electronic control unit is adapted to the change of the combination of the electrical equipment without changing the hardware arrangement. In this case, an alarm for key-forgotten state and a room lamp are both provided normally, and motors for locking and unlocking an electric door lock system are provided optionally so that they can be replaced by other electrical equipment such as electric flexible outer mirrors or other devices.

BACKGROUND OF THE INVENTION
 1. Field of Invention
 The invention relates to an on-vehicle electronic control unit for
 controlling electrical equipment.
 2. Description of Related Art
 In recent years, automobiles have been provided with various electrical
 equipment such as an electric door lock systems, electric flexible outer
 mirrors and similar devices. The electrical equipment to be provided
 differs depending on the type and grade, etc., of an automobile as well as
 the utility of the automobile, i.e., a commercial car, etc.
 Conventionally, electronic control units for controlling the electrical
 equipment are arranged and mounted on automobiles in a manner such that a
 dedicated electronic control unit is provided for each combination of
 electrical equipment mounted on the vehicle.
 Thus, the conventional electronic control units are required to be
 manufactured such that the number of types of dedicated electronic control
 units is same as the number of types of combinations of electrical
 equipment. As a consequence, since the microcomputer and the print circuit
 board of the electronic control unit are required to be designed and
 manufactured independently depending on the type of the combination of
 electrical equipment, there arises a problem that the cost of the
 electronic control unit becomes expensive and the management of the parts
 thereof becomes complicated.
 SUMMARY OF THE INVENTION
 Therefore, in view of the aforesaid problem of the conventional art, an
 object of the invention is to provide an on-vehicle electronic control
 unit, wherein all types of combinations of electrical equipment can be
 controlled by the electronic control unit via a common arrangement without
 changing the arrangement of the microcomputer and the print circuit board,
 or similar device, so as to reduce the number of parts of the on-vehicle
 electronic control unit to a large extent and reduce its cost.
 In order to achieve the aforesaid object, an on-vehicle electronic control
 unit provided in a vehicle for controlling electrical equipment mounted
 thereon comprises an input terminal electrically connectable to at least
 one type of arbitrary input side electrical equipment among multiple types
 of electrical equipment capable of being mounted on the vehicle; an output
 terminal electrically connectable to at least one type of arbitrary output
 side electrical equipment among the multiple types of electrical equipment
 capable of being mounted on the vehicle; a switching terminal which
 receives a signal representing which ones of the multiple types of
 electrical equipment are connected to the input and output terminals; and
 a control means connected to the input, output and switching terminals,
 the control means having multiple types of control modes such that the
 control mode can be changed in accordance with the type of combination of
 the multiple types of electrical equipment to be connected to the input
 and output terminals, and the control means changing its control mode in
 accordance with the signal inputted through the switching terminal to
 another control mode corresponding to the combination of electrical
 equipment represented by the signal and controlling the output side
 electrical equipment connected to the output terminal in accordance with
 the input signal inputted from the input side electrical equipment through
 the input terminal.
 Preferably, the control means includes a memory portion storing multiple
 types of control programs, in accordance with the type of the output side
 electrical equipment to be connectable to the output terminal, for
 controlling the output side electrical equipment connected to the output
 terminal in accordance with the input signal inputted from the input side
 electrical equipment through the input terminal; a control portion for
 controlling the output side electrical equipment connected to the output
 terminal on a basis of the input signal inputted from the input side
 electrical equipment through the input terminal in accordance with the
 control program read from the memory portion; and a switching portion for
 informing the control portion of one type of control program to be read
 corresponding to the output side electrical equipment connected to the
 output terminal from the multiple types of control programs stored in the
 memory portion on the basis of the signal inputted through the switching
 terminal so as to change the control mode of the control means into the
 control mode corresponding to the combination of the electrical equipment
 connected to the input and output terminals.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
 FIG. 1 is a block diagram showing an arrangement of an on-vehicle
 electronic control unit according to an embodiment of the invention, and
 FIG. 2 is a block diagram showing an arrangement of a microcomputer
 provided in the electronic control unit. The electronic control unit 1 is
 provided with a battery input terminal Tb and a ground terminal Tg
 electrically connected to the anode and cathode electrode terminals of a
 battery 3, respectively, input terminals Ti1 to Ti8, and output terminals
 To1 to To3. Each of these terminals Tb, Tg, Ti1 to Ti8 and To1 to To3 is
 connected to the microcomputer (control means) 5 provided in the unit 1
 through a certain circuit. The input terminals Ti7 and Ti8 of the input
 terminals Ti1 to Ti8 correspond to switching terminals of the invention.
 In the electronic control unit 1, the control of an alarm 11 for a
 key-forgotten state and a room lamp 13, both provided normally in a
 vehicle, and the control of various electrical equipment provided
 optionally, can be performed by the common arrangement without changing
 the arrangement of the microcomputer 5, the print circuit board or other
 devices. In this embodiment, examples of the electrical equipment provided
 optionally include an electrical door lock system, electrical flexible
 outer doors, a fuel opener for electrically opening a lid of a fuel supply
 opening, a trunk opener for electrically opening a trunk, and left and
 right side cornering lamps 15 and 17 (see FIG. 6) for illuminating a
 direction to which a vehicle changes its running direction interlocked
 with blinkers (flashers). While, in the present embodiment, the alarm 11
 is provided in the electronic control unit 1, the alarm may be provided
 outside of the unit 1.
 Of the input terminals Ti1 to Ti8, the input terminals Ti1 to Ti4 receive
 signals required at the time of controlling the alarm 11 for a
 key-forgotten state and the room lamp 13, both of which are normally
 provided. The input terminals Ti5 and Ti6 receive signals required at the
 time of controlling the optionally provided electrical equipment, and the
 input terminals Ti7 and Ti8 receive switching signals for changing the
 control mode of the microcomputer 5 in accordance with the type of
 optionally provided electrical equipment. Of the output terminals To1 to
 To3, the output terminal To1 connects the unit to the room lamp 13, and
 the output terminals To2 and To3 connect the unit to the optionally
 provided electrical equipment.
 The battery input terminal Tb and the microcomputer 5 are connected by a
 power supply line through a diode 21 and a constant voltage circuit 23.
 The ground terminal Tg is connected to a ground line which is connected to
 the respective portions of the electronic control unit 1. Connection lines
 L1, L2 for connecting the input terminals Ti1, Ti2 and the input terminals
 of the microcomputer 5 through resistors R1, R2 are grounded through
 resistors R3, R4, respectively, so that low level signals are inputted to
 the microcomputer 5 through the connection lines L1, L2 in a state where
 the input terminals Ti1, Ti2 are electrically opened, respectively.
 Connection lines L3 to L8 for connecting the input terminals Ti3 to Ti8 and
 the input terminals of the microcomputer 5 through resistors R5 to R10 are
 connected to the battery through resistors R11 to R16, respectively, so
 that high level signals are inputted to the microcomputer 5 through the
 connection lines L3 to L8 in a state where the input terminals Ti3 to Ti8
 are electrically opened, respectively. The microcomputer 5 also receives a
 clock signal outputted from an oscillation circuit 25.
 A plurality of connection lines, that is, four connection lines L9 to L12
 in this embodiment, are connected to the output terminals of the
 microcomputer 5. The connection line L9 is connected to the output
 terminal To1 through a resistor R17 and a switching transistor Tr1. The
 connection line L10 is connected to the alarm 11 through a resistor R18
 and a switching transistor Tr2. The connection line L11 is connected to
 the output terminal To2 through a resistor R19, a transistor Tr3 and a
 relay switch 27. The connection line L12 is connected to the output
 terminal To3 through a resistor R20, a transistor Tr4 and a relay switch
 29.
 Each of the transistors Tr1 to Tr4 is turned on and off in accordance with
 the high and low levels of the output signal from the microcomputer 5,
 respectively. In this embodiment, when the transistor Tr1 is turned on,
 the output terminal To1 is grounded. When the transistor Tr2 is turned on,
 the alarm 11 is turned on to output an alarm. When the transistors Tr3 and
 Tr4 are turned on, current is supplied to the relay coils 27a, 29a of the
 relay switches 27, 29, so that each of the movable contacts 27b, 29b of
 these relay switches is shifted from the connection position connected to
 a ground side contact to the connection position connected to a battery
 side contact. Thus, each of the output terminals To2 and To3 is changed
 from the grounded state to the state being connected to the battery. In
 this manner, the movable contacts 27b, 29b connected to the battery side
 contacts are shifted to the ground side contacts in response to the
 turning-off of the transistors Tr3, Tr4, respectively.
 The microcomputer 5 includes a memory portion 5a formed by a read only
 memory (ROM) storing control programs (including control data) necessary
 for controlling the electrical equipment, a control portion 5b for
 controlling the respective electrical equipment on the basis of the
 control program and the control data stored in the memory portion 5a, and
 a switching portion 5c for changing the control mode of the control
 portion 5b in accordance with the combination of the electrical equipment
 to be controlled. The control portion 5b and the switching portion 5c are
 formed by a central processing unit (CPU) and a random access memory (RAM)
 or similar devices.
 As shown in FIG. 3, the memory portion 5a stores therein a first control
 program 30a for controlling the normally provided electrical equipment of
 the alarm 11 and the room lamp 13, and second to fifth control programs
 30b to 30e for controlling the optionally provided electrical equipment of
 the electrical door lock system, the electrical flexible outer doors, the
 fuel opener and the trunk opener, and the cornering lamps 15, 17,
 respectively.
 The switching portion 5c receives the switching signals for changing the
 control mode through the connection lines L7, L8. The electronic control
 unit 1 of this embodiment is arranged so as to be accorded with the four
 combinations of electrical equipment, that is, the combination of the
 normally provided electrical equipment of the alarm 11 and the room lamp
 13 and the electrical door lock system, the combination of the normally
 provided electrical equipment and the electrical flexible outer doors, the
 combination of the normally provided electrical equipment and the set of
 the fuel opener and the trunk opener, and the combination of the normally
 provided electrical equipment and the cornering lamps 15, 17. The signal
 levels of the switching signals to be inputted into the microcomputer 5
 through the connection lines L7, L8 are changed by opening and/or
 grounding the input terminals Ti7, Ti8, whereby the signal levels of the
 switching signals represent which one of the four combinations is
 selected, that is, which of the optionally provided electrical equipment
 is selected.
 In this embodiment, the levels of the respective switching signals inputted
 through the connection lines L7, L8 are changed into (low, low)(FIG. 1),
 (high, low) (FIG. 4), (high, high) (FIG. 5) and (low, high) (FIG. 6)
 depending on whether the electrical door lock system, the electrical
 flexible outer doors, the set of the fuel opener and the trunk opener, and
 the cornering lamps 15, 17 are selected as the optionally provided
 electrical equipment, respectively.
 When the microcomputer 5 is supplied with power, the switching portion 5c
 recognizes the combination of the electrical equipment to be controlled on
 the basis of the signal levels of the inputted switching signals, and then
 instructs the control portion 5b on one of the second to fifth control
 programs 30b to 30e to read in on the basis of the recognition result. The
 control portion 5b, which already reads in the first control program 30a
 in response to the power supply thereto, reads the one of the second to
 fifth control programs 30b to 30e instructed by the switching portion 5c
 in response to the instruction from the control portion 5b. Thus, the
 control mode of the control portion 5b is shifted to that corresponding to
 the combination of the electrical equipment to be controlled, so that the
 control portion 5b controls the respective electrical equipment on the
 basis of the control program 30a and the one of the control programs 30b
 to 30e thus read.
 The relationship between the electronic control unit 1 and the normally
 provided electrical equipment is discussed below. An ignition switch 31
 provided at an ignition key cylinder, an accessory switch 33, a key
 detection switch 35 for detecting the key insertion state, and a courtesy
 switch 37 for detecting the opening and closing of the doors are connected
 to the input terminals Ti1 to Ti4, respectively. The input signals
 inputted into the microcomputer 5 through the connection lines L1 to L4
 change between the high and low levels depending on the on and off states
 of the switches 31, 33, 35 and 37, respectively.
 When the courtesy switch 37 is turned on in response to the opening of the
 door thereby to change the input signal inputted into the microcomputer 5
 through the connection line L4 from the high level to the low level, the
 microcomputer 5 detects that the door has been opened and hence changes
 the output signal outputted through the connection line L9 from the low
 level to the high level to turn on the transistor Tr1 and turn on the room
 lamp 13. In contrast, when the input signal inputted into the
 microcomputer 5 through the connection lines L4 changes from the low level
 to the high level, the microcomputer 5 detects that the door has been
 closed and hence changes the output signal outputted through the
 connection line L9 from the high level to the low level to turn off the
 room lamp 13.
 In a state where the key detection switch 35, having been turned on due to
 the insertion of the key into the ignition key cylinder and hence the
 input signal inputted into the microcomputer 5 through the connection line
 L3, is in the low level, if the microcomputer 5 detects that the door has
 been opened through the turning-on of the courtesy switch 37, the
 microcomputer 5 changes the output signal outputted through the connection
 line L10 from the low level to the high level to turn on the transistor
 Tr2, thereby to operate the alarm 11 so as to notify a driver of the
 key-forgotten state.
 The relationship between the electronic control unit 1 and the optionally
 provided electrical equipment is explained with reference to FIGS. 1, 4, 5
 and 6. In FIG. 1, the positive and negative terminals of each of motors
 41a to 41d, respectively provided at the doors for locking and unlocking
 the corresponding doors, are connected in parallel to the output terminals
 To2 and To3. An operation switch 43 for accepting a user's operation input
 is connected to the input terminals Ti5 and Ti6. The motors 41a to 41d and
 the operation switch 43 form the electric door lock system. In this
 arrangement, both the input terminals Ti7 and Ti8 are grounded.
 The operation switch 43 includes a grounded movable contact 43a interlocked
 with an operation portion (not shown) and two contacts 43b, 43c connected
 to the input terminals Ti5, Ti6, respectively. The movable contact 43a is
 selectively connected to one of the contacts 43b and 43c when the
 operation portion is operated so as to lock or unlock the door, and
 automatically restored to a state being connected to none of the contacts
 43b and 43c in response to the cancellation of the operation to the
 operation portion.
 When the microcomputer 5 detects that one of the input signals inputted
 therein through the connection lines L5 and L6 has been changed from the
 high level to the low level, the microcomputer changes one of the output
 signals outputted to the transistors Tr3 and Tr4 from the low level to the
 high level, thereby to drive the motors 41a to 41d to rotate forwardly or
 reversely to lock or unlock the respective doors.
 When the operation switch 43 is operated to connect the movable contact 43a
 of the operation switch 43 to the contact 43b, thereby to change the input
 signal inputted to the microcomputer 5 through the connection line L5 from
 the high level to the low level, the output signal outputted to the
 transistor Tr4 from the microcomputer is maintained in the low level, but
 the output signal outputted to the transistor Tr3 is changed from the low
 level to the high level. Thus, the transistor Tr3 is turned on while the
 transistor Tr4 is kept in the off state, so that the movable contact 27b
 of the relay switch 27 is shifted from the ground side to the battery
 side, while the movable contact 29b of the relay switch 29 is maintained
 connected to the ground side. As a consequence, the respective motors 41a
 to 41d are supplied with power through the output terminals To2, To3 and
 rotated to the forward direction thereby to lock the doors.
 When the operation switch 43 is operated to connect the movable contact 43a
 of the operation switch 43 to the contact 43c, thereby to change the input
 signal inputted to the microcomputer 5 through the connection line L6 from
 the high level to the low level, the output signal outputted to the
 transistor Tr3 from the microcomputer 5 is maintained at the low level,
 but the output signal outputted to the transistor Tr4 is changed from the
 low level to the high level. Thus, the transistor Tr4 is turned on while
 the transistor Tr3 is maintained in the off state, so that the movable
 contact 29b of the relay switch 29 is shifted from the ground side to the
 battery side, while the movable contact 27b of the relay switch 27 is
 maintained connected to the ground side. As a consequence, the respective
 motors 41a to 41d are supplied with power through the output terminals
 To2, To3 and rotated to the reverse direction thereby to unlock the doors.
 In FIG. 4, the positive and negative terminals of each of motors 51a and
 51b, respectively provided at the left and right electric flexible outer
 mirrors for driving the mirrors to close and open the mirrors, are
 connected in parallel to the output terminals To2 and To3. An operation
 switch 53 for accepting a user's operation input is connected to the input
 terminal Ti5. The mirrors can be opened and closed by operating the
 operation switch 53. In this arrangement, both the input terminals Ti6 and
 Ti7 are opened and the input terminal Ti8 is grounded.
 The operation switch 53 is turned on when an operation portion (not shown)
 is operated and turned off in response to the cancellation of the
 operation to the operation portion. When the operation switch 53 is turned
 on, the input terminal Ti5 is grounded through the operation switch 53, so
 that the signal inputted into the microcomputer 5 through the connection
 line L5 is changed from the high level to the low level.
 The microcomputer 5 recognizes the opening and closing state of the
 mirrors. When the microcomputer detects that the input signal inputted
 therein through the connection line L5 has been changed from the high
 level to the low level, the microcomputer changes the level of one of the
 output signals outputted to the transistors Tr3 and Tr4 respectively
 through the connection lines L11 and L12 from the low level to the high
 level, so that the motors 51a and 51b are driven and rotated forwardly or
 reversely thereby to change the respective mirrors from the opened state
 to the closed state (housed state) or vise versa.
 In FIG. 5, the positive terminal of a motor 61 provided at the trunk opener
 for opening (or unlocking) the trunk is connected to the output terminal
 To2, and the positive terminal of a motor 63 provided at the fuel opener
 for opening the lid of the fuel supply opening is connected to the output
 terminal To3. Further, operation switches 65 and 67 for accepting a user's
 operation inputs for operating the trunk opener and the fuel opener are
 connected to the input terminals Ti5 and Ti6, respectively. In this
 arrangement, the negative terminals of the motors 61 and 63 are grounded
 and both the input terminals Ti7 and Ti8 are opened.
 The operation switches 65 and 67 are turned on when operation portions (not
 shown) are operated and turned off in response to the cancellation of the
 operations to the operation portions. When the operation switches 65 and
 67 are turned on, the input terminals Ti5 and Ti6 are grounded through the
 operation switches 65 and 67, so that the signals inputted into the
 microcomputer 5 through the connection lines L5 and L6 are changed from
 the high level to the low level, respectively.
 When the microcomputer 5 detects that each of the input signals inputted
 therein through the connection lines L5 and L6 has been changed from the
 high level to the low level, the microcomputer changes the output signals
 outputted to the transistors Tr3 and Tr4 respectively through the
 connection lines L11 and L12 from the low level to the high level, whereby
 the motors 61 and 63 are supplied with power through the output terminals
 To2 and To3, thereby to open the trunk and the lid of the fuel supply
 opening.
 In FIG. 6, the right and left cornering lamps 17 and 15 are connected to
 the output terminals To2 and To3, respectively, and a blinker switch 71
 for turning on and off the blinkers is connected to the output terminal
 Ti5 and Ti6, so that the cornering lamps 15 and 17 are controlled on the
 basis of the signal outputted from the blinker switch 71. In this
 arrangement, the input terminal Ti7 is grounded and the input terminal Ti8
 is opened.
 The blinker switch 71 includes a grounded movable contact 71a interlocked
 with an operation portion (not shown) and two contacts 71b, 71c connected
 to the input terminals Ti5, Ti6, respectively. The movable contact 71a is
 selectively connected to one of the contacts 71b and 71c when the
 operation portion is operated in accordance with a change of the running
 direction of a vehicle, and automatically restored to a state being
 connected to none of the contacts 71b and 71c when the change of the
 running direction of the vehicle has been completed and the steering wheel
 of the vehicle is restored.
 When the microcomputer 5 detects that the blinker switch 71 is operated at
 the time of changing the running direction of the vehicle, and the level
 of one of the input signals inputted to the microcomputer through the
 connection lines L5 and L6 is changed from the high level to the low
 level, the microcomputer changes the level of the corresponding one of the
 output signals respectively outputted to the transistors Tr3 and Tr4
 through the connection lines L11 and L12 from the low level to the high
 level, until the level of the aforesaid one of the input signals inputted
 to the microcomputer is restored from the low level to the high level. In
 response to the fact that the level of the aforesaid one of the input
 signals inputted to the microcomputer has been restored from the low level
 to the high level, the microcomputer changes the level of the
 corresponding one of the output signals outputted to the transistors Tr3
 and Tr4 having been set at the high level to the low level. As a
 consequence, the corresponding one of the cornering lamps 15 and 17 is
 supplied with power through the output terminal To2 or To3, whereby the
 cornering lamp 15 or 17 associated with the direction to which the vehicle
 changes its running direction, that is, the cornering lamp on the same
 side as the blinker which is blinking, is turned on during a period where
 the associated blinker is turned on.
 FIG. 7(a) is a diagram showing the relationship between a wire harness 81
 and the electronic control unit corresponding to the combination of the
 electrical equipment shown in FIG. 1, FIG. 7(b) is a diagram showing a
 wire harness 83 corresponding to the combination of the electrical
 equipment shown in FIG. 4, FIG. 7(c) is a diagram showing a wire harness
 85 corresponding to the combination of the electrical equipment shown in
 FIG. 5, and FIG. 7(d) is a diagram showing a wire harness 87 corresponding
 to the combination of the electrical equipment shown in FIG. 6. In the
 respective wire harnesses 81, 83, 85 and 87, the corresponding portions
 are labeled with the same reference numerals and the explanation thereof
 is omitted.
 The wire harnesses 81, 83, 85 and 87 are provided, as the common
 arrangement, with connectors 81a, 83a, 85a and 87a connected to the
 connector 91 of the electronic control unit 1, respectively, and further
 each of the wire harnesses is provided with a connector 93 for connecting
 the electronic control unit 1 to the anode and cathode electrode terminals
 of the battery and the room lamp 13, and a connector 95 for connecting the
 electronic control unit 1 to the ignition switch 31, accessory switch 33,
 key detection switch 35 and courtesy switch 37.
 Individually, the wire harness 81 is provided with a connector 97 for
 connecting the electronic control unit 1 to the respective motors 41a to
 41d for the electric door lock system, and a connector 99 for connecting
 the input terminals Ti5 and Ti6 of the electronic control unit 1 to the
 operation switch 43 and for connecting the input terminals Ti7 and Ti8
 thereof to the ground.
 The wire harness 83 is provided with a connector 101 for connecting the
 electronic control unit 1 to the respective motors 51a to 51d for the
 electric flexible outer mirrors, and a connector 103 for connecting the
 input terminal Ti5 of the electronic control unit 1 to the operation
 switch 53 and for connecting the input terminal Ti8 thereof to the ground.
 The wire harness 85 is provided with a connector 105 for connecting the
 electronic control unit 1 to the respective motors 61 and 63 of the trunk
 opener and the fuel opener, and for connecting the input terminals Ti5 and
 Ti6 of the electronic control unit 1 to the operation switches 65 and 67,
 respectively.
 The wire harness 87 is provided with a connector 107 for connecting the
 input terminals Ti5 and Ti6 of the electronic control unit 1 to the
 blinker switch 71, and for connecting the input terminal Ti7 thereof to
 the ground, and a connector 109 for connecting the electronic control unit
 1 to the left and right cornering lamps 15 and 17.
 In the respective wire harnesses 81, 83, 85 and 87, the connectors 81a,
 83a, 85a and 87a of the electronic control unit 1 side are connected to
 the respective connectors 93, 95, etc. connected to the respective
 electrical equipment, etc. through predetermined wires 81b, 83b, 85b and
 87b, respectively. The connector 91 and the connectors 81a, 83a, 85a and
 87a are made common in standards, such as configuration or the like, so
 that any one of the connectors 81a, 83a, 85a and 87a of the wire harnesses
 81, 83, 85 and 87 can be connected to the connector 91 of the electronic
 control unit 1.
 FIG. 8 is a flow chart showing the control operation of the microcomputer 5
 provided in the electronic control unit 1. In step S1, when the electronic
 control unit 1 is connected to both the battery 3 and the respective
 electrical equipment, and the power is initially supplied to the
 microcomputer 5, a predetermined initialization is performed, and then the
 first control program 30a for controlling the normally provided electrical
 equipment of the alarm 11 and the room lamp 13 is read from the memory
 portion 5a and stored in the control portion 5b. Then, the process
 proceeds to step S2.
 In step S2, it is determined by the switching portion 5c whether or not
 both the input terminals Ti7 and Ti8 are grounded, that is, whether or not
 both the switching signals inputted into the microcomputer through the
 connection lines L7 and L8 are at the low level. If it is determined Yes
 in step S2, the process proceeds to step S3, in which the second control
 program 30b for controlling the electric door lock system is read from the
 memory portion 5a and stored in the control portion 5b. Then, the process
 proceeds to step S4. In contrast, if it is determined No in step S2, the
 process proceeds to step S5.
 In step S5, it is determined by the switching portion 5c whether or not the
 input terminal Ti7 is opened and the input terminal Ti8 is grounded, that
 is, whether or not the switching signals inputted into the microcomputer
 through the connection lines L7 and L8 are at the high and low levels,
 respectively. If it is determined Yes in step S5, the process proceeds to
 step S6, in which the third control program 30c for controlling the
 electric flexible outer mirrors is read from the memory portion 5a and
 stored in the control portion 5b. Then, the process proceeds to step S4.
 In contrast, if it is determined No in step S5, the process proceeds to
 step S7.
 In step S7, it is determined by the switching portion 5c whether or not
 both the input terminals Ti7 and Ti8 are opened, that is, whether or not
 both the switching signals inputted into the microcomputer through the
 connection lines L7 and L8 are at the high level. If it is determined Yes
 in step S7, the process proceeds to step S8, in which the fourth control
 program 30d for controlling the fuel opener and the trunk opener is read
 from the memory portion 5a and stored in the control portion 5b. Then, the
 process proceeds to step S4. In contrast, if it is determined No in step
 S7, the process proceeds to step S9, in which the fifth control program
 30e for controlling the cornering lamps 15 and 17 is read from the memory
 portion 5a and stored in the control portion 5b. Then, the process
 proceeds to step S4.
 In step S4, the control portion 5b controls the respective electrical
 equipment on the basis of the control programs 30a to 30e read in steps
 S1, S3, S6, S8 and S9.
 As described above, according to the present embodiment, when the levels of
 the switching signals inputted into the microcomputer 5 are changed by
 grounding and/or opening the input terminals Ti7 and Ti8, one of the
 control programs 30a to 30e stored in the memory portion 5a corresponding
 to the combination of the electrical equipment to be controlled is read in
 accordance with the levels of the inputted switching signals and read into
 the control portion 5b, whereby the control mode of the control portion 5b
 is set to one corresponding to the combination of electrical equipment to
 be controlled. Accordingly, various kinds of combinations of electrical
 equipment to be mounted on a vehicle can be controlled by the electronic
 control unit of the common arrangement without changing the arrangement of
 the microcomputer 5, the print circuit board or similar devices, whereby
 it becomes possible to reduce the number of parts of the electronic
 control unit to a large extent and reduce a cost thereof.
 In particular, conventionally, multiple types of ROMs storing the dedicated
 control programs corresponding to the respective electrical equipment to
 be controlled are prepared in accordance with the types of electrical
 equipment to be mounted optionally on a vehicle, that is, in accordance
 with the types of electrical equipment to be controlled. Then, the type of
 ROM to be used is changed in accordance with the type of combination of
 the electrical equipment. As a consequence, since the number of types of
 ROMs to be prepared becomes large, the problems arise that the developing
 cost and the management cost are increased, and that an incorrect type of
 ROM may be employed erroneously.
 In contrast, in the present embodiment, the memory portion (ROM) 5a of the
 microcomputer 5 stores multiple types of control programs 30a to 30e
 corresponding to the types of combinations of electrical equipment to be
 connected to the electronic control unit 1, and one of the control
 programs 30a to 30e is selectively read upon request. Accordingly, in the
 present embodiment, since various types of combinations of electrical
 equipment can be controlled by using only one type of ROM, the developing
 cost and the management cost can be reduced to a large extent, and it
 becomes possible to eliminate the problem that an incorrect type of ROM
 may be employed erroneously.
 Further, in the present embodiment, the connector 91 of the electronic
 control unit 1 is made common in standards such as configuration or the
 like with the connectors 81a, 83a, 85a and 87a of the wire harnesses 81,
 83, 85 and 87 corresponding to the respective types of combinations of the
 electrical equipment. Accordingly, the connector 91 of the electronic
 control unit 1 can be used commonly for the various types of combinations
 of the electrical equipment, so that the number of parts of the electronic
 control unit can further be reduced and the manufacturing cost thereof can
 also be reduced.
 In the aforesaid embodiment, the situation where the electronic control
 unit 1 is adapted to the four types of combinations of electrical
 equipment has been described. However, the invention may be arranged to
 increase the types of electrical equipment to be controlled and the types
 of combinations of electrical equipment to be accorded by increasing the
 number of the input terminals Ti1 to Ti6 for inputting signals required
 for control, the number of the input terminals Ti7 and Ti8 for inputting
 the switching signals and the number of the output terminals To1 to To3
 upon request. In this case, the number of the electrical equipment to be
 controlled may be changed at every type of combination of electrical
 equipment.
 As described above, according to the invention, the respective pieces of
 electrical equipment are controlled such that the control means, which has
 multiple types of control modes corresponding to the types of combinations
 of the electrical equipment to be controlled, changes its control mode to
 one which corresponds to the type of combination of the electrical
 equipment connected to the input and output terminals on the basis of the
 signal inputted through the switching terminal. Accordingly, various types
 of combinations of electrical equipment can be controlled by the
 electronic control unit of the common arrangement without changing the
 arrangement of the microcomputer, the print circuit board or the like,
 which makes it possible to reduce the number of parts of the electronic
 control unit to a large extent and reduce the cost thereof.