John 996 TT Cab

I have a 2004 996 TT Cab and Nav is standard on the car. Question is, when the weather gets hot (and the top is down so no a/c) after about 20 minutes of driving the Nav System display scrambles totally. Can't see/read Nav or any audio or other screens.

Anyone have any idea(s) on how to trace/correct?

Thanks very much,

John in Vancouver

ltc

Sounds like you've lost DC cooling (fans) in the PCM.

I would first start by going to the dealer for a quick PIWIS readout; a thermal event should record a DTC.

In any event, if it can be reproduced (if it's raining, I would imagine running the car closed wtih the heater ON ...) the dealer should be able assist.
Worst case would be a new PCM, assuming you can not get the current one repaired (depends on warranty status).

SSST

You could try running the AC even with the top down. The center vent runs behind and over the top of the nav, so this might provide enough cooling to keep the unit from scrambling.

ltc

No, I don't think so.
The PCM was not designed that way.

John 996 TT Cab

Thanks very much for the suggestions.

It takes far more heat than the heater can generate even with the roof closed. Mid to upper 80's F.

The car is off warranty of any kind. Could my "Indie" run the test? Not sure what a PIWIS readout and what a DTC is? Are these read through the OBD II reader?

Any idea of price range on new DCM?

John in Vancouver

ltc

If your Indy has a PIWIS, yes. Not sure you can access it via Durametric, never tried.
A dealer should charge $50, since it is very quick to run a scan.

No idea what a new PCM costs, Sunset or Suncoast can provide the best price (probably 2000) but you would likely need a quick trip to the dealer to make sure S/W is up to date ... Again, 30 min job via PIWIS.

You can sometimes find them for sale here and other sites (eBay), from folks who have done aftermarket installs.
You might also be able to contact Becker and send it in for repair.
Either of these is cheaper than a new unit.

DTC is an error code (diagnostic test code), which almost all modules in the car are capable of storing in order to assist debug.

ltc

Next time the screen "scrambles", take a pic and post it...I am curious.

SSST

I know it won't cool it directly, but I did pull the horseshoe after running the car for a while with tha AC on. It was noticeably cooler behind the horshoe around the PCM.

I know it's not a permanent fix, but it doesn't cost anything to try it.

ltc

Just don't think it is a worthwhile exercise, given the problem described and the design of the PCM.

John 996 TT Cab

Thanks everyone for the input. I'll talk to the Dealer and the Indie. Picture looks like when an old B &W TV's horizonatal hold went wild (boy that dates me!) except its in colour. I am in good standing with the dealer as I spend a ton of $ on accessories and parts.

John in Vancouver

John 996 TT Cab

Has the PIWIS test done by my Indie (no cost). No error codes.
I'm going to upgrade to an aftermarket Nav/Bluetooth/Radio so that I can then also get current mapping as even my dealer can't get me upgrades to the maps and also would like to be able to run the Nav and listen to CD's simultaneously (don't have the multi disc unit).

Looking seriously at the Kenwood 9180 with a Mobridge unit to integrate to the car's electronics.

John in Vancouver