Reviewing all of the engine code faults on a 996, I see no link with the radio! http://www.renntech.org/forums/index...pcode&code=dme

 

So am I to understand this right. One cannot add an aftermarket radio or head unit to the GT3 cause the cars computer will not let it start becuase there is no "radio" present?

I wanted to add an after market sub and head unit with intergrated Nav and Sat radio. Will I still be able to do this?

 

No -- just can't use the stock stereo/amp wiring, due to the MOST bus fiber optic hook-up.

 

Wait...

Can I add an aftermarket radio and sub to my GT3?

 

Well there seems to be some misinformation floating around regarding the GT3 and the MOST bus. According to KarlS, when he removed the CDR-23, it's was not connected via fibre optics to a most bus...
http://www.renntech.org/forums/index.php?showtopic=1649

So it begs the question gentlemen...Is it or isn't it most????

 

I just had my 2003 GT2 radio replaced with an Eclipse NAV, cd/ dvd. I replaced all speakers and added an amp. The old radio was not in anyway connected by fiber optic. It was in fact the same basic head found on 99-01 cars.

 

Thanks for the clarification Larry. From what I have read, the MOST system is used by the radio to connect it to external CD changers, amps, and processors... none of which is used on the GT cars.

 

OK, so I talked with the tech at the dealer today. He told me that the DME checks for the presence of a CDR-23 and when it doesn't find one it generates a fault code, which he showed me on the PST2. This checking is part of the electronic anti-theft system that replaced the old code method in 2003.

The headunit is not connected to a MOST bus, there is no MOST fiber in a GT3. However, it is connected to a CAN bus, which is a wire based bus system that is used for component to component communication within the car. There is a CAN controller in the dash and when it couldn't find the CDR-23, it to reported a fault.

For some reason that even the PCNA techs can not explain, the presence of these faults caused the DME to stop sending a signal to the AC compressor to turn on (whatever happened to good ole relays?).

Now for the best part. To correct it, the tech unplugged the yellow C1 connector on the back of the Traffic Pro. On the TP, this connector is simply used to provide line out connectors for use of an external amplifier. I haven't been able to find a wiring diagram for the CDR-23, so I can only guess that some pin(s) on this connector must be used for the CAN bus. By disconnecting it, the CAN controller no longer "sees" anything connected and goes on its merry way. The AC now works again, as does the Traffic Pro.

I think the same thing can probably be accomplished by using the PST2 to tell the DME that the car has no radio. The dealer didn't want to try this and I was already in to them for a bunch of labor for diagnostics, so I'll have to wait and verify this later.

For those of you who are installing aftermarket headunits or TrafficPros, if you have a problem with your AC, you now know what to do.

Karl

 

Thanks for the clarification Karl...Sounds like some unecessary technology to me...(CAN BUS)

 

If you're into data logging the CAN bus provides quite a bit of data. Or so I understand, I haven't looked closely yet as a data logging system is a low priority project for now.

 

Most data loggers (Motec, Pi, AIM) can plug into the CAN bus for rpm, temps, oil pressure, rpm, etc., making it much cheaper and easier to install because you don't need a lot of external sensors.

Karl

 

Thanks Karl. I knew there was some good point to all this newfangled electronic engine gadgetry added since my '70 T was built. Now to find somebody that wants to buy my Weber float guages.