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SAE J2366 - Family of ITS Data Bus (IDB) Protocol Standards

This Fact Sheet was written on Jul 12, 2006. The statuses of the standards at the time were as follows: SAE J2366-1 (published November 2001), SAE J2366-1L (published November 2001), SAE J2366-2 (published November 2001), SAE J2366-4 (published March 2002), SAE J2366-7 (published April 2002).

This Fact Sheet was written on July 12, 2006.

This Fact Sheet was last verified on October 14, 2009

 Check the ITS Standards Search to see if there has been subsequent development activity.


The ITS Data Bus (IDB) is a common communications network interface for in-vehicle components including consumer electronic devices such as navigation systems, satellite radio receivers, and other devices. The IDB is a serial communications bus, based on the industry standard for Controller Area Networks (CAN) that allows consumers to add or upgrade their devices over the lifetime of their vehicle.

The long development time required to produce a new automobile and the short development time of today's consumer electronic devices has meant that the electronics in a vehicle might lag the state of the art by several years. With the growing consumer-oriented electronics content in today’s vehicles, it is becoming more difficult for the automotive manufacturers to meet consumers’ expectations for electronic devices in vehicles. The result is increasing pressure on the vehicle manufacturers from after-market electronics suppliers, who can update and expand their product lines quickly. Currently, no manufacturers are using these IDB standards, they are looking instead at using other standard interfaces like IDB-1394 (based on IEEE-1394 Firewire) for multimedia in-vehicle applications.

This fact sheet covers the major standards that describe IDB-C, the first set of IDB specifications for CAN that were published in 2001-2002. It addresses the following standards that define the four layers of the IDB-C protocol stack:

  • SAE J2366-1 IDB-C Physical Layer specifies the Physical Layer of the Intelligent Transportation Systems (ITS) Data Bus and is based on Controller Area Networks (CAN), which is generally intended for in-vehicle use. It describes the line drivers/receivers, bus topology and termination, and the physical IDB-C connector. The IDB-C is designed to allow disparate consumer, vehicle, and commercial electronic components to communicate and share information across a standard, open data bus. The Physical Layer of the IDB-C incorporates the CAN 2.0B specification per SAE J2284-2, with some modifications.
  • SAE J2366-2 IDB Link Layer describes the IDB-C Link Layer which is logically divided into two sub-layers namely the Logical Link Control (LLC) and Media Access Control (MAC). The LLC sub-layer provides the mechanisms to send and receive point-to-point and broadcast frames to other LLC sub-layers on the IDB-C. It provides the functionality required to handle access by more than one media trying to send data frames simultaneously on the IDB-C. It also provides functions such as virtual token handling, addressing, and notifications of IDB-C configuration changes to other MAC layers on the IDB-C.
  • SAE J2366-4 IDB Thin Transport Layer describes the Thin Transport Layer of the Intelligent Transportation Systems (ITS) Data Bus, which is generally intended for in-vehicle use. The Thin Transport Layer sits between SAE J2366-2 and J2366-7. It provides the handling of such activities as the packetizing of long messages and message reassembly. The design of the messages and headers has stressed economy, in terms of bits within a CAN 2.0B frame, for more efficient transport.
  • SAE J366-7 IDB Application Message Layer defines an Application Message Layer, which is designed to be part of a complete protocol stack with the other protocol layers in the SAE J2366 family. The Application Message Layer provides application message support for devices that are interconnected via a bus or network. The SAE J2366-7LX--ITS Data Bus Application Message Layer Lexicon, which includes all the parameters defined for use in the application layer, is now combined (as an appendix) with SAE J2366-7 to provide for a quicker revision process in the future.

Another standard in this family, SAE J2366-1L Low Impedance Stereo Audio (LISA), describes the Low Impedance Stereo Audio (LISA) bus, which may be used in conjunction with the Physical Layer of the IDB-C, as described in SAE J2366-1. The audio arbitration messages used to control access to the LISA bus are specified in SAE J2366-7.

What are these standards for?

IDB-C is an open, non-proprietary serial communications protocol designed to allow a wide variety of consumer devices to share information across a common network in the vehicle. The IDB has been developed by the SAE ITS Data Bus Committee with the support of the Consumer Electronics Association (CEA) division of the Electronics Industry Association (EIA). Its primary goal is to provide a means of connecting consumer devices to a common network in a vehicle without requiring the consumer electronics manufacturers to develop interfaces to the different proprietary original equipment manufacturer (OEM) vehicle buses, nor to have to complete automotive-type safety and interoperability qualifications on every product which might be added to the vehicle.

Who uses them?

The IDB is intended to be used by vehicle manufacturers to prepare their vehicles for consumer electronics devices, and by the consumer electronics manufacturers to be able to build one interface for their products that can be used in any vehicle. Additionally, it may be used by the after market electronics industry to simplify integrated installation of add-on automotive electronics. The ultimate users are the consumers, the vehicle buyers, who will be able to configure their vehicles much the same way as they configure their home theaters and personal computers. A quick survey in March 2006, including contact with the IDB Forum ( indicates that no vehicle or consumer electronics manufacturers are currently using the IDB-C standards. The IDB Forum is currently focused on IDB-1394, a family of specifications designed for high-speed multimedia applications that are based on the IEEE-1394 FireWire standards.

How are they used?

The documents define the complete operation of the IDB-C. Equipment designers can use these documents to develop software drivers and hardware interfaces for their products so that they will be "IDB-compliant."


The IDB specifications encompass the definition of the physical medium (unshielded twisted pair), the topology (multidrop bus), media access control mechanisms (token passing), initialization of an IDB network, plug-and-play insertion and removal of devices, message fragmentation and defragmentation, guaranteed delivery of messages, and the application message syntax.

The four standards: SAE J2366-1 Physical Layer; SAE J2366-2 Link Layer; SAE J2366-4 Thin Transport Layer; and SAE J2366-7 Application Message Layer, define the different layers of the IDB protocol stack.

Related documents

The following ITS standards are related and should be considered when using this family of standards:

The following standards and documents, while not part of the ITS standards, should also be considered when using this standard:

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