SAE J1978_200204

Foreword
1 Scope
   1.1 Purpose
   1.2 Differences from ISO Document
2 References
   2.1 Applicable Publications
        2.1.1 SAE Publications
        2.1.2 ISO Publications
   2.2 Related Publications
        2.2.1 ISO Documents
3 Terms and Definitions
4 Required Functions of the External Test Equipment
5 Communication Protocols
6 Connections to the Vehicle
7 Network Access
   7.1 Automatic Determination of Communication Interface
   7.2 Handling of No Response from the Vehicle
   7.3 Handling of Multiple Responses from the Vehicle
   7.4 Message Structure
   7.5 Diagnostic Trouble Codes Monitoring
   7.6 Obtain and Display OBD Emissions Related Current
        Data, Freeze Frame Data, and Test Parameters and
        Results
   7.7 Code Clearing
   7.8 On-Board Diagnostic Evaluations
        7.8.1 Completed On-Board System Readiness Tests
        7.8.2 Supported On-Board System Readiness Tests
        7.8.3 Malfunction Indicator Lamp - Status and Control
   7.9 Use of StopCommunication Service Associated with ISO
        14230-4 (optional)
8 User Interface
   8.1 Display
   8.2 User Input
9 Power Requirements
   9.1 Vehicle Battery Voltage
        9.1.1 Vehicle Battery Voltage for 12 V DC only
        9.1.2 Vehicle Battery Voltage for 12 V DC and 24 V DC
   9.2 Vehicle Battery Current Consumption
10 Electromagnetic Compatibility (EMC)
11 Conformance Testing
   11.1 General
   11.2 Determine OBD Communication Type
   11.3 On-Board System Readiness Test
   11.4 Select Functions
   11.5 Select and Display
   11.6 Confirm Requests to Clear Codes
   11.7 General Diagnostic Communication Tests
   11.8 Capacitance and Impedance at the Diagnostic Connector
   11.9 Operating Voltage and Current Requirement
   11.10 Protocol Check
   11.11 Alphanumeric Display
   11.12 User Manual and Help Facility
12 Notes
   12.1 Marginal Indicia

Specifies: a. A means of establishing communications between an OBD-equipped vehicle and external test equipment, b. A set of diagnostic services to be provided by the external test equipment in order to exercise the services, c. Conformance criteria for the external test equipment.

This SAE Recommended Practice supersedes SAE J1978 FEB1998, and is technically equivalent to ISO/DIS 15031-4:December 14, 2001.This document is intended to satisfy the requirements of an OBD scan tool as required by U.S. On-Board Diagnostic (OBD) regulations.The document specifies:aA means of establishing communications between an OBD-equipped vehicle and external test equipment,bA set of diagnostic services to be provided by the external test equipment in order to exercise the services defined in SAE J1979,cConformance criteria for the external test equipment.