Failure diagnosis method of vehicle communication network
First Claim
1. A failure diagnosis method of a communication network for a vehicle that is constructed by an electronic control device and a plurality of electronic control instruments provided with a failure diagnosis portion being connected to a main line of a multiplex communication line comprising the steps of:
- storing different diagnosis trouble codes respectively, at a failure diagnosis portion of the electronic control device, when the electronic control instrument is malfunctioning, or when an abnormality including disconnection or short circuit has occurred in a communication line from the main line of the multiplex communication line to a branch line that is connected to the electronic control instrument;
measuring a resistance value of the main line resistance in the multiplex communication line; and
identifying an abnormality portion in the communication network by a combination of the measured resistance value of the main line and the diagnosis trouble code that is stored in the failure diagnosis portion.
1 Assignment
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Accused Products
Abstract
When a resistance value of a CAN bus main line is 60 Ω, the CAN bus main line is in a normal state. However, the resistance value thereof differs depending on an abnormality portion when an abnormality such as disconnection, short circuit, or the like has occurred in it or a branch line. Therefore, the abnormality portion can be identified depending on the measured resistance value.
In addition, a failure diagnosis portion of an ECU stores different diagnosis trouble codes in the memory for the following cases; when an abnormality has occurred in the CAN bus communication, when various sensors are malfunctioning, and when an abnormality such as disconnection has occurred in a communication line that is connected to the various sensors. Accordingly, the resistance value of the CAN bus main line is measured, and the abnormality portion can be identified by a combination of the resistance value and the diagnosis trouble code.
20 Citations
7 Claims
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1. A failure diagnosis method of a communication network for a vehicle that is constructed by an electronic control device and a plurality of electronic control instruments provided with a failure diagnosis portion being connected to a main line of a multiplex communication line comprising the steps of:
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storing different diagnosis trouble codes respectively, at a failure diagnosis portion of the electronic control device, when the electronic control instrument is malfunctioning, or when an abnormality including disconnection or short circuit has occurred in a communication line from the main line of the multiplex communication line to a branch line that is connected to the electronic control instrument;
measuring a resistance value of the main line resistance in the multiplex communication line; and
identifying an abnormality portion in the communication network by a combination of the measured resistance value of the main line and the diagnosis trouble code that is stored in the failure diagnosis portion. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification