JP4033141B2 - Electronic control device for vehicle - Google Patents

Description

  The present invention relates to an electronic control device for a vehicle, and more particularly to a control target device such as an engine of a vehicle when a predetermined switch signal (hereinafter referred to as an ignition switch) input from the outside such as an ignition switch or a key switch is turned off. The present invention relates to an electronic control device for a vehicle that performs predetermined control processing such as evaporation gas leak check.

  For example, an engine control device that controls an engine of a vehicle is generally configured to operate by being supplied with operating power from a battery when an ignition switch of the vehicle is turned on. However, in recent years, there is a demand to execute a specific control process at a certain timing even when the engine is stopped with the ignition switch turned off.

  An example of such a specific control process is an evaporation gas leak check of an evaporation purge system. The evaporation purge system is for preventing evaporative gas fuel (hereinafter referred to as evaporation gas) generated in a fuel tank from being released into the atmosphere. In this evaporation purge system, as disclosed in, for example, Patent Document 1, the evaporation gas is temporarily adsorbed on the adsorbent of the canister, and the evaporation gas adsorbed on the canister is released from the atmospheric hole of the canister according to the operating state of the engine. The engine is configured to be purged and burned into the engine intake pipe together with fresh air to be sucked.

  In this evaporation purge system, if a hole, a crack, or the like is generated in the evaporation tank or the evaporation passage between the fuel tank and the canister, the evaporation gas is released to the atmosphere without being adsorbed by the canister. In order to prevent air pollution due to such a failure of the evaporation purge system, an evaporation gas leak check is performed to detect an evaporation gas leak.

  In the evaporation gas leak check, the presence or absence of a failure of the evaporation purge system (that is, evaporation gas leakage) is diagnosed by detecting the pressure fluctuation inside the evaporation purge system with a solenoid valve or the like in a sealed state.

However, such a leak check makes it difficult to perform an accurate diagnosis because the fuel in the fuel tank is likely to evaporate after a long time operation with a high engine load. For this reason, it is conceivable to start the host microcomputer of the engine control device and perform an evaporative gas leak check when a certain time has elapsed after the ignition switch is turned off.
JP-A-8-35452

  As described above, in order for the host microcomputer of the engine control device to perform an evaporative leak check when a certain time has elapsed since the ignition switch was turned off, a timer circuit (soak timer) that starts the host microcomputer by measuring the certain time ) Must be provided.

  However, if this soak timer becomes abnormal, the evaporative gas leak check will not be performed correctly. Therefore, it is necessary to monitor the host microcomputer for the presence or absence of an abnormality in the soak timer, and to detect if an abnormality occurs. .

  In order to detect an abnormality in the soak timer, for example, the history of starting the host microcomputer at the set time of the soak timer is stored in the standby RAM (SRAM) in the host microcomputer, and then the ignition switch is turned on to start the host microcomputer. In this case, there is a method of determining whether or not an abnormality has occurred in the soak timer based on the relationship between the presence / absence of the SRAM activation history and the counter value in the soak timer.

However, in this method, when the host microcomputer is activated by the soak timer, if the operating power supplied to the host microcomputer is lowered to a level where the activation history cannot be correctly written to the SRAM, the activation history is correctly written to the SRAM. There is a possibility that things cannot be done. As a result, when the ignition switch is turned on next time and a diagnosis determination is made, there is a problem that the abnormality of the soak timer is erroneously detected.The present invention has been made in view of the above points. It is an object of the present invention to provide an electronic control device for a vehicle that can reliably leave a start history of a microcomputer even when a supply operating voltage when activated by a circuit is relatively low.

In order to achieve the above-described object, an electronic control device for a vehicle according to claim 1 comprises:
A microcomputer for controlling the control target device mounted on the vehicle;
A first power supply circuit that starts supplying operating power to the microcomputer when a predetermined switch signal input from the outside is turned on and stops supplying operating power based on the switch signal being turned off; ,
A counter and a register for storing a determination value for determining whether or not the count value by the counter has reached a predetermined time, and the counter counts an elapsed time after the switch signal is turned off. A timer circuit for outputting a start signal for starting the first power supply circuit when the count value reaches the determination value, and supplying operation power to the microcomputer from the first power supply circuit;
A second power supply circuit for supplying operating power to the timer circuit even after the switch signal is turned off,
The microcomputer performs predetermined control processing when the first power supply circuit is activated by the timer circuit and receives supply of operating power, and changes the judgment value stored in the register when the predetermined control processing is executed. It is characterized by doing.

  Here, for example, assuming that the microcomputer includes an SRAM and the microcomputer startup history is written in the SRAM, the writeable voltage to the SRAM is usually higher than the minimum operating voltage of the microcomputer. Even if a predetermined control process is executed after being activated, a situation may occur in which the activation history cannot be written to the SRAM. On the other hand, the setting value stored in the register can be changed with the minimum operating voltage of the microcomputer.

  Therefore, in the vehicle electronic control device according to the first aspect, when the microcomputer executes a predetermined control process, the activation history of the microcomputer is left using a register in the timer circuit. Specifically, the register in the timer circuit normally stores a determination value for determining whether or not the count value by the counter has reached a predetermined time, but when executing a predetermined control process by the microcomputer, The judgment value is changed to a different value. Thereby, even when the operating voltage is relatively low, when the microcomputer is activated, the activation history can be left in the register.

  As described in claim 2, after the determination value is changed by the microcomputer, the timer circuit may prohibit the output of the start signal again. Thus, the microcomputer is not activated again by the activation signal from the timer circuit, so that the changed value can be reliably stored in the register.

  As a specific configuration for prohibiting the re-output of the start signal from the timer circuit, the microcomputer can change the determination value to a value outside the range that can be counted by the counter, as described in claim 3. It is possible to prohibit the re-output of the start signal from. In this case, as described in claim 4, the counter starts the count operation from the time when the switch signal is turned off, and stops the count operation when reaching a predetermined limit value. By configuring so that the set value is changed to a value exceeding the set value, the set value can be changed to a value outside the range that the counter can count.

  Further, as in claim 5, when the timer circuit outputs the start signal, the determination value stored in the register is referred to, and if the determination value is changed by the microcomputer, the start signal is output. Even if the prohibit circuit is configured to be prohibited, it is possible to prohibit the output of the start signal from the timer circuit again.

  The electronic control device for a vehicle according to claim 6 is configured such that when the microcomputer receives an operation power supply from the first power supply circuit and starts operation due to the switch signal being turned on, the count value of the counter And a setting value of the register, it is determined whether or not the microcomputer startup process by the timer circuit is normal.

  That is, when the counter value of the counter has reached the initial register setting value and the setting value has been changed, and when the counter value has not reached the initial setting value, the register If it is held, it can be determined that the microcomputer startup process by the timer circuit is normal. Conversely, if the set value has not been changed even though the counter value has reached the original set value, and the set value has been changed even though the counter value has not reached the original set value. If this is the case, it can be determined that the microcomputer startup process by the timer circuit is abnormal.

  In the above-described electronic control device for a vehicle, as described in claim 7, the microcomputer controls the engine of the vehicle, and executes a process of diagnosing the evaporation purge system of the engine as a predetermined control process. It is suitable as a thing.

  Embodiments of an electronic control device for a vehicle according to the present invention will be described below with reference to the drawings. In this embodiment, an example in which the vehicle electronic control device is applied to an engine control device that controls the engine of the vehicle will be described. However, the vehicle electronic control device can also be applied as a control device for other in-vehicle devices.

  FIG. 1 shows an overall configuration of an engine control device (engine ECU) 1 in the present embodiment. As shown in FIG. 1, the engine ECU 1 mainly operates the host microcomputer 3 that executes various processes for controlling the operating state of the engine and the ignition switch (IGSW) 13 to operate the host microcomputer 3. Timer circuit 5 for counting the time during which the timer is stopped, a power supply circuit 7 for outputting a 5 v operating voltage Vos for operating the timer circuit 5, and a power source for outputting a 5 v operating voltage Vom to the host microcomputer 3 Circuit 11.

  The power supply circuit 7 is constantly supplied with a battery voltage VB from a battery 15 of the vehicle. The power supply circuit 7 generates an operating voltage Vos from the battery voltage VB and outputs it to the timer circuit 5 and the volatile memory (SRAM) 32 of the host microcomputer 3.

  The timer circuit 5 is used to determine the timing for performing an evaporative gas leak check described later. That is, when the host microcomputer 3 is instructed to start the count operation when the host microcomputer 3 stops its operation when the IGSW 13 is turned off, the timer circuit 5 starts the count operation, and the counter 36 And a register 38 for storing a set value for determining that the count value has reached a predetermined time.

  The counter 36 and the register 38 are connected to the comparator 40, and the count value of the counter 36 and the set value of the register 38 are compared in the comparator 40. When the count value exceeds the set value, the comparator 40 outputs a high-level power activation signal TSW. This power activation signal TSW is given to the relay coil of the main relay 9 via the OR circuit 42, and turns on the relay contact. Thereby, the battery voltage VB is supplied to the power supply circuit 11 via the main relay 9, and the power supply circuit 11 generates the operation voltage Vom and outputs it to the host microcomputer 3. The predetermined time counted by the timer circuit 5 is set to 5 hours, for example.

  Further, the timer circuit 5 includes a communication I / F 34 for communicating with the host microcomputer 3. Through this communication I / F 34, the host microcomputer 3 receives a count operation start instruction of the counter 36 and a set value to be rewritten in the register 38. Further, the count value of the counter 36 and the setting value stored in the register 38 are output to the host microcomputer 3 via the communication I / F 34.

  The OR circuit 42 connected to the relay coil of the main relay 9 includes, in addition to the power supply start signal TSW from the comparator 40, an IGSW signal indicating the on / off state of the IGSW 13 and the host microcomputer 3 via the IGSW 13 of the vehicle. The power holding signal PI from is input. Therefore, either when the high-level power supply activation signal TSW is output from the comparator 40, when the IGSW 13 of the vehicle is turned on, or when the high-level power holding signal PI is output from the host microcomputer 3. Is established, the relay coil of the main relay 9 is energized and the relay contact is turned on.

  The host microcomputer 3 includes a non-volatile memory 20 including a flash ROM for storing a control program and the like, a CPU 22 that executes control processing of the engine and the like, an evaporative purge and a leak check, which will be described later, in accordance with the program stored in the non-volatile memory 20 A volatile memory 24 such as a RAM for temporarily storing calculation processing results, etc., an I / O port 26 for inputting a starter signal STA and a shift position signal for an automatic transmission and outputting a control signal to an ignition device and a fuel injection device Used for controlling the A / D converter 28 that performs A / D conversion of sensor signals necessary for control, such as engine intake pressure and water temperature, the communication I / F 30 that communicates with the timer circuit 5, and the engine And a volatile memory 32 such as a standby RAM for storing learning control data.

  Here, the learning control data is, for example, a correction coefficient learning value for bringing the air-fuel ratio state in the engine closer to the theoretical air-fuel ratio, or a sensor correction learning value for correcting a shift in output due to aging of each sensor. is there. Each time the vehicle is driven, such a learning value is updated based on the state of a control target device such as a sensor signal or an engine. The latest learning value is temporarily stored in the volatile memory 32, At this timing, the data is transferred to the nonvolatile memory 20.

  Such a learning value needs to be continuously held by the volatile memory 32 even when the supply of the operating voltage Vom from the power supply circuit 11 to the host microcomputer 3 is stopped. The power supply circuit 7 is configured to receive the operating voltage Vos.

  In the present embodiment, when the host microcomputer 3 starts to operate upon receiving the operation voltage Vom from the power supply circuit 11, first, the power holding signal PI to the OR circuit 42 is set to the high level, and the operation voltage Vom from the power supply circuit 11. Is maintained. On the other hand, when the host microcomputer 3 determines that the predetermined operation stop condition is satisfied, the host microcomputer 3 sets the power holding signal PI to the low level, stops the supply of the operating voltage Vom from the power supply circuit 11, and stops its own operation.

  The operation stop condition in the present embodiment is established when the host microcomputer 3 is activated when the IGSW 13 is turned on, and when the necessary processing ends after the IGSW 13 is turned off. When the host microcomputer 3 is started when the power supply start signal TSW of the timer circuit 5 becomes high level when the timer circuit 5 is turned off, it is established when necessary processing such as an evaporation gas leak check of the evaporation purge system is completed. To do.

  Here, the evaporation purge system and the evaporation gas leak check will be briefly described with reference to FIG. As shown in FIG. 2, the evaporative purge system includes a canister 48 connected to a fuel tank 44 via an evaporative passage 46, and purges evaporative gas from the canister 48 downstream of a throttle valve 52 in an intake pipe 50 of the engine. A purge passage 54 is provided. An electromagnetic purge valve 56 is provided in the purge passage 54, and the purge passage 54 can be opened and closed by the purge valve 56.

  Further, a fresh air introduction passage 58 for introducing fresh air (new atmosphere) into the atmospheric hole 48 a of the canister 48 is formed, and an atmospheric filter 60 is provided in the fresh air introduction passage 58. An electric pump module 62 including an electric pump for applying pressure to the canister 48 is provided at a connection portion between the air hole 48 a of the canister 48 and the fresh air introduction passage 58. In addition to the above-described electric pump, the electric pump module 62 includes an electromagnetic valve that opens and closes the air hole 48a and a pressure sensor that detects the pressure in the canister 48.

  In such an evaporative purge system, normally, the purge valve 56 is closed and the electromagnetic valve of the electric pump module is opened to open the atmospheric hole 48a of the canister 48 to the atmosphere, so that the evaporative gas generated in the fuel tank 44 can be removed. Adsorb to 48. Then, by opening the purge valve 56 according to the operating state of the engine, using the fact that the intake pipe 50 has a negative pressure, together with the air flowing into the air hole 48a of the canister 48 from the fresh air introduction passage 58, The evaporated gas once adsorbed by the canister 48 is purged into the intake pipe 50 and burned by the engine.

  The evaporation gas leak check of the evaporation purge system is executed in the following procedure. First, the purge valve 56 is closed and the electromagnetic valve of the electric pump module 62 is opened to drive the electric pump, and the inside of the canister 48, the evaporation passage 46 and the fuel tank 44 is made negative pressure, and then the electromagnetic valve of the electric pump module 62 is turned on. close. Then, the pressure in the canister 48 is measured every specified time by the pressure sensor of the electric pump module 62. From the change state of each pressure value measured in this way, a failure has occurred in the evaporation purge system, specifically, a hole or a crack has occurred in any of the canister 48, the evaporation passage 46 and the fuel tank 44. Judge whether it is.

  The above-described evaporation gas purge and leak check are executed by the host microcomputer 3.

  Next, processing executed by the host microcomputer 3 will be described based on the flowcharts of FIGS. 3 and 4. FIG. 3 is a flowchart showing the entire process executed by the host microcomputer 3, and FIG. 4 is a flowchart showing the diagnosis determination process of the timer circuit 5 that is executed when the host microcomputer 3 is started.

  As shown in FIG. 3, when the host microcomputer 3 starts operating upon receiving the operation voltage Vom from the power supply circuit 11, first, in step S100, the power holding signal PI to the OR circuit 42 is set to high level to The state where the operating voltage Vom is output from the circuit 11 is maintained.

  In a succeeding step S110, it is determined whether or not the timer circuit 5 is activated. Specifically, the count value of the counter 36 in the timer circuit 5 is read, the count value reaches the set value of the register 38, and whether the power activation signal TSW becomes high level is based on the read count value. judge. That is, in this step S110, it is determined whether the start-up of the host microcomputer 3 is caused by the IGSW 13 being turned on or the power-supply start signal TSW from the timer circuit 5. In this case, the state of the IGSW 13 is read to determine the activation by turning on the IGSW 13, or the level of the power activation signal TSW from the comparator 40 to the OR circuit 42 is directly read to determine the activation by the timer circuit 5. May be.

  If it is determined in step S110 that the timer circuit 5 has started up, the processing from step S120 is executed. In step S120, a leak check of the evaporation purge system is performed according to the above-described procedure. The result of this leak check is written in the volatile memory 32 or the non-volatile memory 20 of the host microcomputer 3, but when it cannot be written due to the operating voltage or the like, it is recorded using an internal counter (not shown) or the like. .

  When the evaporative gas leak check is performed in step S120, the set value of the register 38 of the timer circuit 5 is changed in step S130. This change of the set value will be described with reference to FIG.

  In the present embodiment, as shown in FIG. 5A, the counter 36 of the timer circuit 5 performs a counting operation by counting up from an initial value. The count operation is set to stop when the count value reaches a predetermined upper limit value. However, the counter 36 is not limited to counting up, but may be one that counts down.

  On the other hand, the set value initially stored in the register 38 is set to a value (for example, $ 1D) that matches the count value of the counter 36 when the count operation of the counter 36 is performed for about 5 hours. Then, the initial set value is changed to a value (for example, $ 3F) larger than the upper limit value of the countable range of the counter 36 by the change process of the set value in step S130. Thereby, once the host microcomputer 3 is started by the timer circuit 5 and the set value of the register 38 is changed, it is possible to prohibit the timer circuit 5 from starting the host microcomputer 3 again.

  As a result, the register 38 of the timer circuit 5 can reliably hold the set value after the change and can avoid power consumption due to activation of the host microcomputer 3.

  Next, in step S140, it is determined whether or not the IGSW 13 is turned on. This determination may be made based on the starter signal STA in addition to the IGSW signal. When the IGSW 3 is turned on while the host microcomputer 3 is being activated by the timer circuit 5, the host microcomputer 3 proceeds to step S150 in order to execute engine control such as ignition timing and fuel injection amount. On the other hand, if it is determined in step S140 that the IGSW 13 remains off, the process proceeds to step S200.

  In step S200, the low-level power holding signal PI is output to stop energization from the OR circuit 42 to the main relay 9, and the supply of the operating voltage Vom by the power circuit 11 is stopped.

  Next, processing when the host microcomputer 3 is activated when the IGSW 13 is turned on will be described. In this case, “No” is determined in step S110, or “Yes” is determined in step S140, and the processing after step S150 is performed.

  In step S150, a diagnosis determination process for determining whether or not the timer circuit 5 is normal is performed. The details of the diagnosis determination process are shown in the flowchart of FIG.

  In the diagnosis determination process, as shown in FIG. 4, first, in step S210, the count value of the counter 36 and the set value of the register 38 are read. In step S220, it is determined whether or not the counter value of the counter 36 is greater than a predetermined value ($ 1D) equal to the initial set value of the register 38. If “Yes” is determined in step S220, the process proceeds to step S230, and if “No” is determined, the process proceeds to step S240.

  In step S230, it is determined whether or not the set value of the register 38 has been changed from the initial value ($ 1D), that is, whether or not it is equal to the changed predetermined value ($ 3F). When the count value of the counter 36 exceeds the initial setting value (S1D) of the register 38, if the timer circuit 5 is normal, the host microcomputer 3 is started as shown in FIG. The set value of the register 38 should be changed to a predetermined value ($ 3F). Accordingly, if “Yes” is determined in step S230, the process proceeds to step S250, and it is determined that the timer circuit 5 is normal.

  On the other hand, when the count value of the counter 36 exceeds the initial set value ($ 1D) of the register 38, the set value of the register 38 is not changed to the predetermined set value ($ 3F). As shown in FIG. 5B, it is presumed that some abnormality occurred in the timer circuit 5 and the host microcomputer 3 could not be started. For this reason, when it determines with "No" in step S230, it progresses to step S260 and determines with the timer circuit 5 being abnormal. In this case, abnormality processing such as storing the abnormality code or turning on a warning lamp is performed.

  Further, in step S240 executed when it is determined in step S220 that the counter value of the counter 36 is equal to or less than the initial set value ($ 1D) of the register 38, the set value of the register 38 is set to the initial set value ($ 1D). ) Or not. When the count value of the counter 36 is equal to or less than the initial setting value ($ 1D) of the register 38, if the timer circuit 5 is normal, the host microcomputer 3 is not started, and the setting value of the register 38 is the initial setting value ( $ 1D) should remain. Accordingly, if “Yes” is determined in step S240, the process proceeds to step S250, and it is determined that the timer circuit 5 is normal.

  On the other hand, even though the count value of the counter 36 is equal to or less than the initial setting value ($ 1D) of the register 38, the setting value of the register 38 is changed from the initial setting value ($ 1D) to the predetermined setting value ($ 3F). If it has been changed, there is a possibility that some abnormality has occurred in the timer circuit 5 and the host microcomputer 3 has been activated. For this reason, when it determines with "No" in step S240, it progresses to step S260 and determines with the timer circuit 5 being abnormal.

  After performing the diagnosis determination in this way, as shown in the flowchart of FIG. 3, the process proceeds to step S160, and based on various sensor signals, shift position signals, etc., the ignition timing, the fuel injection amount, the throttle valve Engine control such as opening degree and evaporative gas purge control are executed. In step S170, it is determined whether or not the IGSW 13 is turned off. If the IGSW 13 remains on, the engine control process in step S160 described above is continued.

  If it is determined in step S170 that the IGSW 13 is turned off, the process proceeds to step S180, and it is determined whether or not the activation permission condition for the host microcomputer 3 by the timer circuit 5 is satisfied. Specifically, in the diagnosis determination process shown in the flowchart of FIG. 4, when the timer circuit 5 is determined to be normal, it is determined that the condition is satisfied, and when the abnormality is determined, the condition is not satisfied.

  When it is determined that the activation permission condition by the timer circuit 5 is satisfied, the process proceeds to step S190 to execute timer activation processing. In this timer activation process, the counter 36 is cleared to start the count operation from the initial value, and the set value ($ 1D) is written to the register 38. As a result, when the count value of the counter 36 exceeds the set value ($ 1D) of the register 38, the high-level power activation signal TSW is output from the comparator 40.

  If it is determined that the activation permission condition by the timer circuit 5 is not established, the process proceeds to step S200 without executing the predetermined step S190. In step S200, as described above, the host microcomputer 3 stops its own operation by setting the power holding signal PI to the low level.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the embodiment described above, the leak check of the evaporation purge system is performed only once after the IGSW 13 is turned off. However, the leak check may be performed a plurality of times after the IGSW 13 is turned off. For this purpose, for example, the set value of the register 38 may be changed step by step within the countable range of the counter 36 of the timer circuit 5. Thereby, after the IGSW is turned off, the leak check can be performed a plurality of times, and the number of activations of the host microcomputer 3 by the timer circuit 5 can also be determined from the set value of the register 38 that is changed stepwise.

  In the above-described embodiment, when the host microcomputer 3 is started by the timer circuit 5, the host microcomputer 3 changes the set value of the register 38 to a value outside the countable range of the counter 36. Activation by the circuit 5 was prohibited. However, in order to prohibit the start by the timer circuit 5 again, for example, when a logic circuit including an AND gate or the like is provided between the comparator 40 and the OR circuit 42 and the value of the register 38 is changed, A low level signal may be input to one of the AND circuits. In this case, even if the power supply activation signal TSW is output from the comparator 40, it is not input to the OR circuit 42. Therefore, the host microcomputer 3 can be prohibited from being activated again. Further, when the value of the register 38 is changed, a logic circuit that operates so as to stop the comparison operation of the comparator 40 can be formed.

  In the above case, the host microcomputer 3 may change the set value of the register 38 to an arbitrary set value regardless of the countable range of the counter 36.

1 is a configuration diagram showing an overall configuration of an engine control device (engine ECU) 1 in an embodiment of the present invention. It is a block diagram which shows the whole structure of an evaporation purge system. It is a flowchart which shows the whole process which the host microcomputer 3 performs. 5 is a flowchart showing a diagnosis determination process of the timer circuit 5 that is executed when the host microcomputer 3 is activated by the IGSW 13; (A) is a time chart for explaining activation of the host microcomputer 3 by the timer circuit 5 and diagnosis determination of the timer circuit 5 when the timer circuit 5 is normal, and (b) is a diagram when the timer circuit 5 is abnormal. 6 is a time chart for explaining a diagnosis determination process of the timer circuit 5;

Explanation of symbols

1 ... Engine control device (engine ECU)
3 ... microcomputer 5 ... timer circuit 7 ... power supply circuit,
9 ... Main relay 11 ... Power supply circuit 13 ... Ignition switch (IGSW)
15 ... Battery 36 ... Counter 38 ... Register 40 ... Comparator 42 ... OR circuit

Claims (7)

A microcomputer for controlling the control target device mounted on the vehicle;
When a predetermined switch signal input from the outside is turned on, the supply of operating power to the microcomputer is started, and the supply of the operating power is stopped based on the switch signal being turned off. A power circuit;
A counter and a register for storing a determination value for determining whether or not the count value by the counter has reached a predetermined time, and the counter counts an elapsed time after the switch signal is turned off. A timer circuit for outputting an activation signal for activating the first power supply circuit when the count value reaches the determination value, and supplying operation power to the microcomputer from the first power supply circuit;
A second power supply circuit that supplies operating power to the timer circuit even after the switch signal is turned off;
The microcomputer performs a predetermined control process when the first power supply circuit is activated by the timer circuit and receives a supply of operation power, and is stored in the register when the predetermined control process is executed. An electronic control device for a vehicle characterized by changing a judgment value.   2. The vehicle electronic control device according to claim 1, wherein after the determination value is changed by the microcomputer, the timer circuit prohibits the output of the start signal again. 3.   3. The microcomputer prohibits the output of the start signal from the timer circuit again by changing the determination value to a value outside the range that the counter can count. Electronic control device for vehicles.   The counter starts counting from the time when the switch signal is turned off, and stops counting when reaching a predetermined limit value. The microcomputer sets the value to exceed the limit value. 4. The vehicle electronic control device according to claim 3, wherein the value is changed.   The timer circuit refers to the determination value stored in the register when outputting the activation signal, and prohibits the output of the activation signal when the determination value is changed by the microcomputer The vehicle electronic control device according to claim 2, further comprising a circuit.   Based on the count value of the counter and the set value of the register, the microcomputer starts operation upon receiving operation power from the first power supply circuit due to the switch signal being turned on. The vehicle electronic control device according to claim 1, wherein the microcomputer determines whether or not the activation process of the microcomputer by the timer circuit is normal.   The said microcomputer controls the engine of a vehicle, The process which diagnoses the evaporation purge system of the said engine is performed as the said predetermined | prescribed control process. Vehicle electronic control device.

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