Connect

= Connecting to Consult-II ECUs =

Currently it seems the most straightforward way to connect to these ECUs is through the K line of the OBD2 connector. On more recent vehicles it is probably possible to accomplish the same thing through the OBD2 CAN lines. These are not populated on some vehicles.

K line
Some ECUs support J1979-compliant OBD2 traffic on the K line with the ISO 9141 protocol. This allows only basic, generic stuff like reading / clearing DTCs, freeze frame data etc. This iso9141 connection is established with a standard 5bps "slow init" with 0x33 as the functional address.

On the same K line the ECUs support the "Consult-II" (C2) mode, which is implemented on the iso 14230 protocol. This means :
 * Connection is established and maintained according to iso 14230
 * The mandatory SID 3E is supported (TesterPresent, used as a "keepalive")
 * Some standard SIDs are supported (1A ReadECUIdentification, 21 RDBLI, 22 RDBCI, 27 SecurityAccess, etc.)
 * Some mfg-specific SIDs are implemented (A0, A3, AC)

Some of the standard SIDs have mfg-specific extensions, such as SID 1A with IDOPT 0x81. This is OK, since iso 14230 says IDOPT 0x80-0xFF are ManufacturerSpecific.

To connect to the ECU : speed is 10.4kbps, ISO14230 fast init with Tester addr = 0xFC, dest addr = 0x10, using physical addressing. Usually (always ?) the ECU will support "addressless headers" according to the keywords returned during init. Refer to the 14230 docs for details.

There is a tool to assist with connection and speaking with ECUs - nisprog a.k.a. freediag.