OBD-II Scan Tool
- Ground Vehicle Standard
- J1978_202205
- Revised
Scope
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A means of establishing communications between an OBD-equipped vehicle and an OBD-II scan tool.
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A set of diagnostic services to be provided by an OBD-II scan tool in order to exercise the services defined in SAE J1979/ISO 15031-5.
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Current U.S. OBD regulations will permit ISO 15765-4 as an allowable OBD serial data link at 500 kbps only. Only those provisions of ISO 15765-4 that pertain to 500 kbps are required to be supported by an SAE J1978 diagnostic scan tool.
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Current U.S. OBD regulations will not allow greater than 20 V at the SAE J1962 connector. Only the Type A connector as defined in SAE J1962/ISO 15031-3 needs to be supported by an SAE J1978 diagnostic scan tool.
Rationale
Recommended Content
| Ground Vehicle Standard | Diagnostic Connector |
| Ground Vehicle Standard | Class B Data Communications Network Interface |
| Ground Vehicle Standard | Serial Data Communication Interface |
Topic
Data Sets - Support Documents
Issuing Committee
Vehicle E E System Diagnostic Standards Committee
The committee shall increase customer satisfaction and lower product life cycle costs by investigating and recommending standards that will promote more effective diagnosis of vehicle electrical and electronic system problems. The resulting recommended practices will focus on model year 1992 and beyond. However, they may be useful for prior vehicle diagnosis/repair and may serve as a basis for additional recommended practices and pre-model year 1992 vehicles.Vision Statement: A standard disgnostic connector (in a standard location) will be in all vehicles. Pin assignments for a portion of the connector will also be standardized.All vehicles will implement a set of industry standard diagnostic test modes that can be executed over a standard communication data line (i.e., SAE J1850, ISO 9141-2). Industry standard test information will be associated with some of these diagnostic test modes.An OBD II scan tool will be able to utilize a minimum set of standardized diagnostic test modes and test information.A system will be in place that will allow standard electronic access of all E/E diagnostic service information. Future diagnostic legislation will be in harmony with this vision and the resulting SAE Recommended Practices.
Reference
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