Can bus wiring on early 997 cup w/ ADL2

[pwf]

I'm trying to track down what I think is a can bus termination issue in a 2006 997 Cup with a Motec ADL2.

I haven't been able to find any harness/wiring documentation for the car -- does anyone know how termination was typically setup from the factory?

[MikeD]

I rebuilt a 997 GT3 Cup wiring from the ground up but before reading on please consider to double check as my notes are taken from a MY2008 and I'm not sure if your model year is built the same way, so do your own checks before you cut open all the loom...

As far as I remember one 120R can resistor is within the short 30cm long loom running from ADL2 to the 48-pole connector, most likely within a heatshrink.
The other 120R resistor I'm not 100% sure but probably near the Bosch MS 3.1. ecu or somewhere in the direction of the 5-pole ASL connector that is used for additional loggers or CAN connection to paddle shift and such (located on the right hand side of the car somewhere in the region of the Bosch ECU or B-pillar if I remember correctly).
The Bosch ecu receives CAN wires from the ADL2 and laptrigger beacon on ecu pins F61 (CAN-L) and F45 (CAN-H), and then has PCB internal connections to the other ecus pins F12 (CAN-L) and F29 (CAN-H) where another pair of wires go to the connector for the additional logger with ASL connector, mentioned before.
So in case you disconnect the ECU connector and try to measure the CAN resistance than you will only measure one side of the CAN network, as the other side will only be connected through the ECU when it is actually connected.

How do you come to the conclusion that you have a CAN termination issue at all?

I had to troubleshoot an intermittent CAN communication problem which was a nasty one... near the 48-pole connector (on the short 30cm loom going to the ADL2) where the shield of the CAN wires was cut and heat-shrinked at the end for a nice finish of the shield, someone who built the original loom cut to deep and into one of the CAN wires, just damaged the isolation... not a problem for some years as the wire itself was OK, but after a long time one single f*cking strand of the shield came in contact with the CAN wire, just right next to where they cutted the shield and into the isloation. This one took quite a while to diagnose as this problem was under a proper glue-heatshrinked portion and so it wasn't an area where you'd normally expect a problem at all.