Motor vehicle diagnostic and monitoring device having keep alive memory

• US 4,271,402 A
• Filed: 08/29/1979
• Issued: 06/02/1981
• Est. Priority Date: 08/29/1979
• Status: Expired due to Term

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Kastura, John L., Stewart, William R.
• Primary Examiner(s): Caldwell, Sr., John W.
• Assistant Examiner(s): Nowicki, Joseph E.
• Application Number:
  US06/070,885
• Time in Patent Office: 643 Days
• Field of Search: 340/52 F, 340/518, 340/529, 307/10 R, 364/424, 364/431, 371/25, 371/29
• US Class Current: 340/459
• CPC Class Codes: G07C 5/0808 Diagnosing performance data testing of vehicles G01M17/00; testing of electrical installation on vehicles G01R31/005

Abstract

A diagnostic and warning system for a motor vehicle monitors the condition of a number of preselected parameters. When the condition of the parameters is representative of a fault condition, the system energizes a malfunction light in the vehicle compartment during the period of the detected fault. The particular fault detected is stored in a nonvolatile memory where it is stored independent of the subsequent condition of the respective parameter. The stored fault conditions may thereafter be read from memory to provide an indication of the malfunctions that have occurred in response to a diagnostic interrogation signal. The fault conditions stored in the nonvolatile memory are erased when a predetermined time period has lapsed since the occurrence of a detected fault condition so that old nonrecurring self-correcting faults are not retained in memory and accordingly not indicated in response to a diagnostic interrogation signal.

Claims

1. A diagnostic monitoring system for monitoring the conditions of predetermined parameters in a motor vehicle having a driving compartment comprising, in combination:

a memory nonvolatile as to engine operation having locations for storing detected fault conditions;

fault indicating means in the vehicle driving compartment effective to signal the occurrence of a fault condition;

means effective to (a) detect fault conditions in the predetermined parameters, (b) energize the fault indicating means during detected fault conditions, and (c) store the fault conditions detected in respective locations in the nonvolatile memory;

means effective to respond to a diagnostic interrogation signal for identifying the specific faulted conditions stored in the nonvolatile memory; and

timer means effective to clear from the nonvolatile memory locations at least the stored detected fault conditions for which the timed period since the last detected fault condition exceeds a time that spans a substantial number of engine operating events since detection of a fault condition, whereby old nonrecurring self-correcting faults are cleared from memory and accordingly are not indicated in response to a diagnostic interrogation signal.

2. A diagnostic monitoring system for monitoring the conditions of predetermined parameters in an engine driven vehicle having a battery, a switch selectively operable to start and stop the engine and energize vehicle and engine electrical loads, and a driving compartment comprising, in combination:

a nonvolatile memory having locations for storing detected fault conditions;

fault indicating means in the driving compartment effective to signal the occurrence of a fault condition;

fault detection means effective to (a) compare the condition of each of the predetermined parameters with respective predetermined limits, (b) energize the fault indicating means during the period when the condition of a parameter is representative of a fault condition and (c) store a detected fault condition in a respective location in the nonvolatile memory;

means effective to provide a diagnostic interrogation signal for causing an indication of the faulted conditions stored in the nonvolatile memory;

a nonvolatile engine start counter;

means effective to increment the engine start counter each time the engine is started in response to operation of the switch;

means effective to reset the engine start counter each time a fault condition is detected by the fault detection means; and

means effective to clear from the nonvolatile memory locations the stored detected fault conditions when the count in the engine start counter exceeds a predetermined number, whereby old nonrecurring self-correcting faults are cleared from memory and accordingly not indicated in response to a diagnostic interrogation signal.

3. A diagnostic monitoring system for monitoring the operating conditions of predetermined parameters in a vehicle engine control system comprising, in combination:

a battery;

a switch coupled to the battery selectively operable to start the engine and energize the control system and stop the engine and deenergize the control system;

a memory having locations for storing detected fault conditions and for storing an engine start count;

means effective to couple the battery directly to the memory so that the stored fault conditions and engine start count are retained in memory independent of the operation of the switch;

fault indicating means in the vehicle driving compartment effective to signal the occurrence of a fault condition;

fault detection means effective to (a) compare the condition of each of the predetermined parameters with respective predetermined limits, (b) energize the fault indicating means during the period when the condition of a parameter is representative of a fault condition and (c) store a detected fault condition in a respective location in the memory;

means effective to provide a diagnostic interrogation signal for causing an indication of the faulted conditions stored in the memory;

means effective to increment the engine start count stored in the memory each time the engine is started in response to operation of the switch;

means effective to clear the engine start count in the memory each time a fault condition is detected by the fault detection means; and

means effective to clear from the memory locations the stored detected fault conditions when the engine start count exceeds a predetermined value, whereby old nonrecurring self-correcting faults are erased from memory and accordingly not indicated in response to a diagnostic interrogation signal.