Communication circuit trouble checking apparatus

• US 5,734,322 A
• Filed: 04/05/1996
• Issued: 03/31/1998
• Est. Priority Date: 04/17/1995
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Shinso, Yoshihide, Ishii, Shigeru, Jozaki, Tateki
• Primary Examiner(s): Hofsass, Jeffery
• Assistant Examiner(s): POPE, DARYL C
• Application Number:
  US08/628,168
• Time in Patent Office: 725 Days
• Field of Search: 340/514, 340/428, 340/439, 364/424.034, 364/424.038, 364/424.039, 73/116
• US Class Current: 340/514
• CPC Class Codes: B60R 16/0315 using multiplexing techniques multiplexing for transmission of signals G08C15/00; multiplexing for electrical communication in general H04J
• CPC Class Codes: G08B 29/06 Monitoring of the line circuits, e.g. signalling of line faults

Abstract

An apparatus for checking a trouble in a communication circuit connected between engine and transmission control units. A check signal is produced at uniform intervals of time. The check signal is converted into a predetermined code. The converted code is transmitted through the communication circuit from one of the engine and transmission control units to the other control unit. The code transmitted to the other control unit is monitored to produce a failure signal to indicate that a trouble occurs in the communication circuit when the monitored code is not identical with the predetermined code.

Claims

1. An apparatus for checking a trouble in a communication circuit having a plurality of signal lines each of which is connected to apply a control signal capable of being at either a first level or a second level between engine and transmission control units used to control a power train including an engine and an automatic transmission drivingly coupled to the engine, the trouble checking apparatus comprising:

transmitting unit configured to transmit a check signal having the second level through each of the signal lines, at uniform intervals of time, from one of the engine and transmission control units to a remaining one of the engine and transmission control units; and

a monitoring unit coupled to the signal lines and configured to monitor the levels of the respective check signals transmitted to the remaining control unit to produce a failure signal to indicate that a trouble occurs in the communication circuit when all of the monitored levels of the respective check signals transmitted to the remaining control unit to produce a failure signal to indicate that a trouble occurs in the communication circuit when all of the monitored levels are at the second level.

6. The trouble checking apparatus as claimed in claim 1, wherein the first level is a low level, and the second level is a high level.

2. An apparatus for checking a trouble in a communication circuit connected between engine and transmission control units used to control a power train including an engine and an automatic transmission drivingly coupled to the engine, the trouble checking apparatus comprising:

a signal selector;

means for producing at least one torque down control signal to the signal selector when the engine is required to produce a reduced output, the torque down control signal having a first priority;

means for producing a check signal to the signal selector at uniform intervals of time, the check signal having a second priority lower than the first priority of the torque down control signal;

the signal selector selecting one of the signals having a higher priority upon simultaneous reception of at least two signals applied thereto;

means for converting the torque down control signal into a first predetermined code and the check signal into a second predetermined code;

means for transmitting the converted code of the selected signal through the communication circuit from the transmission control unit to the engine control unit; and

means for monitoring the code transmitted to the engine control unit to produce a failure signal to indicate that a trouble occurs in the communication circuit when the code monitored for the check signal is not identical with the second predetermined code.

3. The trouble checking apparatus as claimed in claim 2, wherein the transmission control unit includes means for producing a lockup control signal to the signal selector, the lockup control signal having a priority lower than the priority of the check signal.

4. An apparatus for checking a trouble in a communication circuit connected between engine and transmission control units used to control a power train including an engine and an automatic transmission drivingly connected to the engine, the communication circuit having a first group of signal lines for transmitting data signals from the transmission control unit to the engine control unit and a second group of signal lines for transmitting data signals from the engine control unit to the transmission control unit, the trouble checking apparatus comprising:

means for producing a check signal at uniform intervals of time;

means for converting the check signal into predetermined voltage levels developed on the respective signal lines of one of the first and second groups to transmit the check signal from one of the engine and transmission control units to a remaining one of the engine and transmission control units; and

means for monitoring the voltage levels transmitted to the remaining control unit to produce a failure signal to indicate that a trouble occurs in the communication circuit when the monitored voltage levels are not identical with the respective predetermined voltage levels.

5. An apparatus for checking a trouble in a communication circuit connected between engine and transmission control units used to control a power train including an engine and an automatic transmission drivingly coupled to the engine, the communication circuit having a first group of signal lines for transmitting signals from the transmission control unit to the engine control unit and a second group of signal lines for transmitting signals from the engine control unit to the transmission control unit, the trouble checking apparatus comprising:

a signal selector;

means for producing at least one torque down control signal to the signal selector when the engine is required to produce a reduced output, the torque down control signal having a first priority;

means for producing a check signal to the signal selector at uniform intervals of time, the check signal having a second priority lower than the first priority of the torque down control signal;

the signal selector selecting one of the signals having a higher priority upon simultaneous reception of at least two signals applied thereto;

means for converting the torque down control signal into a first group of predetermined voltage levels and the check signal into a second group of predetermined voltage levels;

means for transmitting the converted voltage levels of the selected signal through the respective signal lines of the first group from the transmission control unit to the engine control unit; and

means for monitoring the voltage levels transmitted to the engine control unit to produce a failure signal to indicate that a trouble occurs in the communication circuit when the voltage levels monitored for the check signal is not identical with the respective voltage levels of the second group.