johnfm

Once a week or so I experience complete engine cut out when starting from cold. It sometimes happens twice, then starts OK. When it starts OK the tiptronic warning light comes on, so I have to restart to remove this light, then all is fine. It seems as if its an immobiliser thing, as when it cuts out the LED starts to flash immediately and there is a 'click' coming from under the passenger seat area, where the immobilser electronics live.

Any ideas, or should I just live with it??

GeoT3

john, check your dme relay. from what i have read on the 993 board, the dme relay is a component that does give out from time to time. when it goes, the egine will shut off. 993 dme relay is located in the trunk by all the fuses. not sure where it is located in 964s but do blieve its under the pass. seat where the clicking is coming from. also check out the 993 board's archives for info on the pesty dme relay.

Randall G.

Hi John,

George's idea of replacing the DME relay is a good one, considering how inexpensive a new relay is (less than 20 dollars US). If it doesn't fix your problem, keep it as a spare.

The DME relay on a 964 is in the luggage compartment fuse box, same as a 993.

phil@tech9

Johnfm,

Is the idle erratic before it stalls, or does it cut dead ?
Also, does it cut out during it's warm up cycle (as the idle from cold is higher), or is it past this point ?

Adrian

Dear John,
I have heard of this problem before. Now it may not be your problem but this is certainly a problem. Only in the UK and also on 928s. The 964 has a 928 immobiliser system installed if installationw as done by PCGB/Dealer. Power failures caused by corrosion on the pins of this unit can certainly cause your problem. I am only mentioning this because you can hear the clicking from around the passengers seat.
Unfortunately there can be many other reasons but the fact that your TIP warning is also coming on (which has nothing to do with the DME relay, do not discount but not my first choice under the circumstances) says to me a power related, power cut off problem.
If you have an aftermarket system installed it could be more complicated.
Good luck and please keep us informed. I have no diagrams for your setup. One day I will find them. Maybe Phil has something at his place,
Ciao,
Adrian
911C4

PS: Could also be a low voltage condition battery.

johnfm

The car is fitted with a Porsche Immobilser (little black thing which you push into a small slot for 1 second, till you hear a beep. It beeps three times when you pull it out)& Porsche Alarm, both factory fitted. The alarm unit & central locking controller, and another silver box are under the drivers seat(Right hand drive BTW). I am yet to remove the passenger seat, but I expect the DME and the tiptronic unit and the immobiliser are under there somewhere.

In answer to Phil, the engine cuts out dead, it only happens on cold starts in the morning and it is not often, maybe once every 2 weeks. It sometimes does just once, sometimes for 2 or 3 starts. When it starts it is absolutely fine - except for the tiptronic light, but this disappears on restart.

With regard to low voltage condition battery, a possibility, as since I discovered current draining f@@!!"g light in luggage compartment, I haven't had a cut-out, but will keep a check on it.

BTW, it never happens other than at starting, ie never cuts out while idling at traffic lights etc.

I'm not unduly worried, but I can imagine if it is an electrical fault, it may worsen to a point where it refuses to start!

Adrian

Dear John,
The immobiliser works on the DME relay directly not on the DME. DME direct interface was not introduced until the Bosch 5.2 system on the 1996 model year 993s. Getting back to the 964. This little part I do have the wiring diagram for. The end result of such a problem is a failure to start completely.
The last time I helped somebody with such a problem was a 928 GTS (95 model) and the problem was corrosion on the pins of the immobilser unit. The fault was causing the dme relay to de-energise a cutting off the fuel supply and power to the DME.
Information on RHD Porsches is hard to find outside of England. There is nothing in the normal factory manuals and nothing in the wiring diagrams for RHDs. The alarm system is a complete mystery. You should as I said contact PCGB or your local Porsche repair shop for somehelp with the set up.
Ciao,
Adrian
911C4

johnfm

Adrian

are the pins accessible under the passenger seat and cleanable or are they enclosed in a black plastic connector of some sort?

If problem persists, is the unit replacable, or do Porsche now do a completely different immobilser OR should I get a 3rd party (ie Toad Alram/immobilser) fitted?

964Cab

Hi,

I looked at my original 1990 C4 Cab "window sticker" and it notes a, "One Key Central Locking/Alarm System W/ LED Warning Lights". Is that Porsche-speak for "immobilzer" ? I knew I had an alarm system of course but was the "immobilizer" aspect of the alarm system an additional option that's determined when buying the car new ?

Many thanks,

Patrick
'90C4Cab

phil@tech9

Johnfm,

I don't know anybody that has wiring diagrams for this alarm system. They were fitted by the main dealers and PCGB, I think they were made by Gemini.

It is very common for these systems to fail and unless there is any external wiring, socket, corrosion problems that can be found I'm afraid its a case of removing the relevant parts and disposing of them in the bin !

A new alarm/Immobiliser can be installed, but check with your insurance company about the specification that they accept. Most require a Thatcham approval. As a guide it will cost around £350 installed for a new one.

Adrian

Dear Patrick,
The 964 was "never" fitted with an immobiliser at the factory unless "spezial werks" were involved. Special request. As I said and have been supported by Phil. these special alarm requirements were always done by the importer of a specific country and its dealers. Your sticker shows the standard alarm system fitted.
As for fixing the problem. Phil basically says what I would have said. Phil is in the UK and I would certainly taking note of what he says in relation ot UK RHD 964s,
Ciao,
Adrian
911C4

964Cab

Adrian:

I just took out the right seat (USA 964) and I see the radio amp of course but what are those other items: A relay is under the right seat # 954-018-142-00 What the heck is that for ? I have a 5spd. Also there is a nearby silver box with the # 911-617-227-00 and as well there is another smaller box that says "SACHS" and the number 618-112-00 Do you have any idea what these items are ? Are they the immbolizer ?

Thanks,

Patrick
'90C4 Cab USA

Adrian

Dear Patrick,
None of those units are immobilsers. You have under the pax seat of a 1990 model, the rear spoiler control unit, the auxillary spoiler control unit (looks like a relay), cruise control if installed and the radio boost unit. This description only applies to 1989 and 1990 models.
If you had an immobilser unit installed by a Porsche dealer it would be a 928 part number,
Ciao,
Adrian
911C4

964Cab

Adrian:

Which item under the right seat is the cruise control unit ? I ask because I killed it somwhow how when working on other electrical problems. What's that relay for under the passenger seat ?

Thanks,

Patrick

Adrian

Dear Patrick,
The relay is for the rear spoiler. 1989 and 1990 models only.
The cruise control is # 911-617-227-00.
As we have discussed via email. Check the ignition switch. Mine played up this morning and almost duplicated the same problems as you have. The cause was simply by my key ring. It was TOO heavy. I installed a birthday present onto it. A Porsche mini pocket knife. After this mornings little christmas tree this has been removed. I did actually prove that this was the problem by the way. Something to keep an eye on, especially for the high mileage daily driver. The system wears out over time, the key gets a little loose and then a few strange things can occur,
Ciao,
Adrian
911C4