Where do the messages shown on the central display come from?  
Is there one ECU that sources all of the information?
If it is the engine ECU, do all the fault messages displayed also have a fault code from the paperclip?

I'm looking at the "Automatic Gearbox" message that I'm getting, and so wondering if the engine ECU knows about it, but may not be producing a fault code.
Thanks,
Tom

TheBoy wrote on 31. Jul 2008 at 19:14:

Excellent. Thanks for that. This means that only one ECU is responsible for that mesage, and I can trace down this potentially major fault. (I hope it is also the source of the Engine limitation... )
Next step is to interrogate the Gearbox ECU.  Should I be able to read the Gearbox ECU fault codes through the standard test connector under the steering wheel? And do I have to use a Tech2, or is there a different sort of "paperclip" that I can use?

TheBoy wrote on 01. Aug 2008 at 08:49:


Apparently the car was working OK, no reported faults, and then (following an abrupt stop) the gearbox warning came on and the engine speed no longer responded to the pedal.
Is it likley that two completely separate systems would have failed at the same time? Or more likley that (say) the gearbox fault forces a degraded engine operation?
I'm with Mark's DTM Calib, to see if the throttle position is reported correctly by the Engine ECU.  Unless you happen to know if the 'box ECU fault causes the Engine ECU to go into degraded mode by overriding the supply signals to the two position sensors (hardware solution that would override any software faults).  In which case, the Engine ECU is correct in its report, but the cause is still not the actual sensor but the excitation for the sensor.
(Happy to go fully into the technology on this; I work with electronic controllers in the avionics industry.  Just don't know the logic/ground rules for the automotive versions)

My main problem is that I don't have access to a code reader or diagnostic monitor for the ECUs, so can neither monitor the throttle position nor read the gearbox fault codes.  So I'm guessing from the outside.

Unless I can swap in components from the Petrol V6 Auto (same year) to assist diagnosis.
Oh, yes, still waiting for Haynes Manual, too, so anything special to vehicle is outside my knowledge.

TheBoy wrote on 01. Aug 2008 at 16:58:

Thanks for that; the relative scale of protection is not something I'm used to at an automotive level.
Would the accelerator pot be the same item on the V6 as the TD?  So can I swap them around? Not sure the V6 is DBW, but also was surprised to find that the TD is DBW.

And, whilst recognising your comments elsewhere that only a Tech2 will do all the tasks required, would I get any value out of a ELM327 or similar to read the ECU data?  Sounds like a neat bit of kit, but I'm hoping that I won't be getting the use out of it....

TheBoy wrote on 01. Aug 2008 at 21:50:

Would the V6 be DBW? So would it have a TPS pot?

Presumably the deciding factor for the functionality of the reader is the software, which is always the expensive bit.  After all, the interface chip (in this case, ELM327) is standard across a range of products.  Ah, but I suppose it depends if they clock it and buffer it correctly... Never mind; the answer is Tech2, unless you get lucky.

Quote:


So have we, but interfacing with the chips is not the problem . .

Communicating in the correct protocol is the real issue here. 

Tech2 is the only viable solution, and much cheaper than any development work trying to reproduce one.

this software has millions of different protocols!!!!!!!!!!!!! can attempt auto detection aswell its used for interfacing with telecomms equipment but it reckons it has a fair few obd protocols on it