SAE-established OBD II communication standard used by Ford domestic cars and light trucks. One of three hardware layers defined by OBD II.

SAE-established OBD II communication standard used by GM cars and light trucks. One of three hardware layers defined by OBD II.

1994/Amd.1: 1996, Road vehicles — Diagnostic systems — Part 2: CARB requirements for interchange of digital information — Amendment 1

This is a newer version of the ISO9141 protocol. It has a provision for a fast initialization which may be used instead of the slow 5bps handshake sequence.

CAN is becoming the most widely used bus for in-vehicle communications. It is a high speed/high performance protocol.

LIN is a low cost, low speed, in-vehicle network intended to complement the higher performance CAN network. Vehicle systems with modest network requirements are placed on a LIN sub-network to reduce costs. The LIN sub-networks connect to the vehicle’s CAN network via gateways. LIN uses a single-wire enhanced ISO9141 implementation (non-OBDII protocol).

UBP is a Ford defined protocol.

CCD is a Chrysler defined protocol.

ALDL is GM defined protocol.