PROCESS FOR STORING VEHICLE ELECTRONIC PERMANENT FAULT CODE DURING ENGINE ELECTRONIC SHUT DOWN

IP.com Prior Art Database Disclosure
IP.com Disclosure Number: IPCOM000175716D
Publication Date: 20-Oct-2008
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PASIAN Frédéric - Inventor [+1] [-1]
ROCHER Ludovic - Inventor

Abstract

The invention relates to a process for storing permanent vehicle electronic fault code during engine electronic shut down. It is above all useful to avoid deletion of permanent vehicle electronic fault code when a battery disconnection occurs just after engine electronic shut down.The present invention proposes to reduce the ECU post operation duration to a minimum in case of permanent DTC have been detected during the last driving cycle to ensure that the EEPROM flashing operation can take place rapidly without the risk of battery disconnection. The invention consists in forcing non volatile memory flashing just after ignition key is turned off before the ECU carries out the systems shut down operations.

Language

English (United States)

Country

France

Document File

2 pages / 62.7 KB

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Continental Automotive France S.A.S.

Idée : Frédéric Pasian (Lherm, France)

Ludovic Rocher (Pouvourville, France)

PROCESS FOR STORING VEHICLE ELECTRONIC PERMANENT FAULT CODE DURING ENGINE ELECTRONIC SHUT DOWN

FIELD OF THE INVENTION

     The invention relates to a process for storing permanent vehicle electronic fault code during engine electronic shut down. It is above all useful to avoid deletion of permanent vehicle electronic fault code when a battery disconnection occurs just after engine electronic shut down.

PRIOR ART

Nowadays, passenger cars, light and medium duty trucks are equipped with an electronic

On Board Diagnostic System (OBD).

     Such system consists in many electronic sensors, and actuators monitoring the engine and/or vehicle functioning and reporting any malfunction under the form of an electronic fault code or DTC (Diagnostic Trouble Code) to the main engine or vehicle electronic controller (ECU, Engine control unit).

     Upon reception of a DTC, the ECU triggers the necessary diagnostic strategy, which may consists in warning the driver and/or reducing maximum vehicle speed, and so on…

     The ECU receives the DTC and stores it first in its volatile memory, called RAM (Random Access Memory). At the engine shut down, during few minutes, the ECU remains powered by the battery. It carries many systems shut down operations such as engine cooling shut down (engine fan control) and it copies (or flashes) the DTC into its non volatile memory, called EEPROM (Electrically-Erasable Programmable Read Only Memory). This operation, called ECU post operation, cannot be done while the engine is running, as on board computations for the vehicle functioning are taking place in the ECU during this time.

However if a battery disconnection occurs during this ECU post operation phase, the ECU is not powered anymore and the operation to copy DTC into the EEPROM is not done or may be interrupted. This scenario with permanent fault code loss may occur at a garage in case of long post-operating phases (few minutes). The repairman turns off the ignition key, opens the engine bay, and within few minutes disconnects the engine battery, as recommended prior to carry out the engine repair operation.

     The DTC triggered during the last driving cycle, are therefore definitely lost by the system, no diagnostic strategy can take place. This can lead to a non compliance with OBD and/or emissions legislation for example, in case of an after treatment system malfunction which is not detected.

This is this drawback that the present invention proposes to avoid.

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