Problem with board computer

[Troky]

Hi all,

I have problem with board computer on my '91 911turbo. It doesn't count trip kilometers and it doesn't display speed. Only thing that works is digital thermometer and turbo pressure meter. Analog instruments works fine. I think it doesn't get pulses from speed sensor. How can I fix this? Does anyone have pinout for that VDO or something else? Please help.
Thanks.


Troky
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'91 911 turbo

[Don Haney]

Hi Troky.
Im pretty sure I can come up with the wiring harness, but hard to scan due to size. If your local to L.A., feel free to stop in and read the factory Turbo manuals to your hearts content.
I would think the easiest way to diagnose which one of the many relays and sensors have failed would be to have the car plugged in to the Bosch hammer or the next generation factory diagnostic tool. This is about a 10K tool, so you'll want to pay your local Porsche shop to perform this service for you. My 91 C2 has about 88 possible fault codes, so don't try to count the flash codes. I found it was too hard to distinguish one series of flashes from the next series. Needless to say, but what I thought was the problem for the fault code was not. Not all small shops will have this tool, so call around first. Worst case you'll have to make a visit to yours local dealer for this service. Im not sure about the Hammer, but the later tool tell you what is wrong which your Porsche in readable text with the technician sitting in your front seat!
Check your fuses before you do anything else! Your 911 has a built in fuse tester in the relay board if you can not determin if the fuse is good or bad, if you did not know this already.
Good luck,
Don

[Troky]

Hi Don!

Thanks for your answer. I would like to come to L.A.sometimes with my 911, but I live on the other side of the World )
I think I'll have to visit the nearest Porsche service center to solve the problem.

Troky

[JonSeigel]

I always do this and hate to do it again, but I *must* help my fellow 964/965 owner. There is a thread posted right now on the Rennlist.com 964 board regarding installing and troubleshooting trip computers. Those guys will be able to figure out what you need to do.

Good luck!

[Britwrench]

The Porsche laptop (PST2) will only diagnose vehicles from 1996 (OBD2 compliant). You use the Bosch KTS300 (Hammer) for 964 models and it won't diagnose any instrument problems.

Basically, the easiest way is to install a substitue OBC and see if it works. If some of the systems are working you need to check the inputs and the control switch is operating correctly.
It's DMM time!!!

[eion]

Actually, I'm pretty sure that the KTS500 (the new one) will work on OBD1 systems. That aside, it does sound like it's time to either try swapping the OBC out, checking the connections on the tach/OBC (the clock sometimes suffers from solder problems, so it isn't beyond the bounds of probability that the tach could too), or using the wiring diagrams and a digital multimeter. I don't have access to the turbo-specific diagrams, but seeing as your boost gauge works already, I can probably hunt down the relevant OBC wiring diagrams for the non-turbo and that should work fine.

[Britwrench]

You are probably right about the KTS550, but Bosch seem to be reluctant to release it in the US so it's not likely to be widely available. The Porsche PST2 is not the same as the KTS550.
The PST2 is Porsche only applicable, following the trends of all the major Euro makers in making incredibly expensive their-models-only laptops. I wait in interest for 7-8 year old Porsche, BMW, MB and Volvo and see what happens to their resale; anyone want a 8 year old 745i with "minor electrical problems"?

[eion]

Oh, I hadn't realised. I'm trying to get my hands on a refurbished Hammer or equivalent - with no success so far.

[Britwrench]

Saw a Bosch hammer (KTS300) on e-bay recently. If you get one make sure it has the correct lead to plug into the car and the most up-to-date "chip" or module. It also comes with a charger.

They are available, type in "Bosch KTS300" into google or similar.

Be aware it is a basic scan type tool and do not solely rely on fault diagnosis by machine.............

[JasonAndreas]

The 19 pin connector can be purchased by anyone for $497.70 from Bosch USA (12 week ETA). You may be able to buy a KTS550 from BoschUSA for $3,798.35. There are some restrictions to its resale however you should be able to get around them/amend them. They don't sell the KTS500 in the USA. There is a company in taiwan that claims to have custom software/hardware and a source for the connectors for $1995.95 + $1100 for the Porsche specific software.

[Britwrench]

That may all be true. The hammer will do all the diagnosis you will probably ever need for a 964. Anything else can be done with a DMM and/or the Bosch ABS2 tester. All of those items combined are still less than the KTS550 and the allegedly available software.
Don't forget the scan tool can only receive signals that are supplied by the embedded diagnosis sytem of the vehicle.

[tshih]

eion,

The trail may be cold by now but 2-3 months ago I posted a source for the Bosch Hammer refurbished and warranteed by a Scotsman Ranald at rwmotortec.com (had one left for $1550 with cables and software included, shipping as well!). But it may have been snapped up by a member from CA (Tre Cup) who expressed interest.

The new unit may be still available for $3000 from a friendly Porsche dealer (Sunset Porsche in Oregon).

Good luck.
Tom

[Turbo3.6]

Let me know if you need the 965 wiring diagrams. I have the factory manuals and will scan and email them to you.

[Troky]

Yes, man, that would be grat! )
Wiring on my 965 totaly messed up and I want to fix it... Diagrams will help a lot! Thanks.


Troky