Can anyone say if the OBD2 port an a 2002 4.2 XK8 uses the K-line or CAN bus or both for diagnostics to the engine ECU.

 

The 4.2 (I thought introduced in 2003) data link connector uses 3 systems for communication:
CAN, SCP and Serial data link.

I believe K-line normally uses pin 7 for communication. There is no connection to pin 7 in the data link connector.

 

The 4..2 came out on Q4 2002 in the UK, not sure about the rotw.

Well I was a bit surprised when I used my AE cable as it indicated that it was connecting using ISO-9141 which uses the K-line.

Are there any diagrams showing the obd topology or a list showing which bus is used for which module?

 

The topology is in section 21 here: http://www.jagrepair.com/images/Auto.../jagxk2003.pdf

Just FYI, the topology changed significantly with the switch from the 4.0 to the 4.2.

 

Hmm, well thats odd, Ill have anothar play around with it tonight.

 

My reader definitely uses the ISO-9141 protocol (on a UK car)

 

What is the plan?

 

This video shows just a few features, it also does lots of other stuff, dyno plots, 0 to 60, 0 to 100 timing etc. All data comes from the diagnostics port using a proprietary VAG protocol.

Since Kin now has a Jag I am thinking about adapting it, but it will be a fair amount of effort so there are no timescales.

It started life just as a boost gauge, that grew legs.

liquidA3 (8P Chassis) test run - YouTube

 

Haven't mastered the onboard networks yet, but the Serial Data Link (ISO 9141) is used for Diagnostics at 10.4 Kbaud.

But I think the IDS is also communicating via the CAN bus to the ECU, as I can monitor that traffic, and the IDS gets much more data per second than via standard OBDII interfaces (so Kline then).