Help needed with 2004 Porsche 996 GT3 CAN Bus install

[tga]

I'm planning to install a DL1 in a 2004 Porsche 996 GT3, and would like to log engine RPM. On the pre-CAN bus cars, there was a square-wave RPM signal on the OBD-II port. I believe this signal no longer exists on the CAN bus 9x6 cars (but I haven't confirmed this), so I think I need a CAN bus interface to get engine RPM.

Ideally, I'd want to tap into the CAN bus under the dash and run it to the DL1 interface. The OBD-II CAN interface isn't really an option; the first time I shift on the track my leg will knock out the connector (plus I want a more permanent install anyway).

I was hoping someone could answer these questions:

- Are the ECU CAN interface and OBD-II CAN interface essentially identical hardware, with just a different configuration and interface connector (OBD vs DB9)?
- Can the ECU CAN connector be re-configured to the OBD CAN configuration (the DB9 will be easier to connect to).
- Can I cut off the OBD connector and splice into the the CAN bus under the dash?
- Has anyone figured out the channel config for Porsche's CAN bus?

I want to make sure this all works before spending $200...

Thanks.

[Support]

- Are the ECU CAN interface and OBD-II CAN interface essentially identical hardware, with just a different configuration and interface connector (OBD vs DB9)?

Yes absolutely identical. To enable OBD-II you just tick a box, at which point you are reduced from 15 CAN channels to 14 CAN channels as one is used for the OBD-II data. It is supplied with a cable to go from the 9 way d-type on the interface to the OBD-II connector


- Can the ECU CAN connector be re-configured to the OBD CAN configuration (the DB9 will be easier to connect to).

You can just connect directly to the 9 way d-type if you like, we can provide information on how the two connectors are wired together.


- Can I cut off the OBD connector and splice into the the CAN bus under the dash?

Yes, you could connect from the d-type connector directly in to the CAN bus on the vehicle, you would need to add a termination resistor somewhere.



- Has anyone figured out the channel config for Porsche's CAN bus?

I'm afraid I can't help you out with any information on this.


Regards,

Martin

[Andreas Lidstr]

Great info for me who are a bit confused about CAN hardware.

If using the "ODBII-CAN", do you have full speed and acces to the CAN channels or is it slower/lower sampling rates?

Is it only ECU-info to be able to get via the OBD or is it possible to get all CAN channels this way at full speed?

Hope you understand my questions...no one else do.