Porsche Enthusiasts Club Forum

Hi all

I Have a Porsche that has been sitting idle for almost 18 months now since developing this fault, so if anyone can help please.

The vehicle in question is a 944S2 3.0 ltr 1990 model.

Here is the story:

Parked the car up as it needed work for it's MOT.... with one thing and another days turned into weeks, but each week the car was religeously started up.

The battery went flat AND WAS REMOVED FROM THE CAR to charge it. When the battery was re-fitted to the car the alarm sounded, this was the first time I had ever heard the alarm sound, after a while we managed to shut off the alarm by locking and unlocking the car, but from this moment on the car has failed to start.

I'm convinced the porsche alarm has somehow imobilised the engine, its just too much of a coinsidence. Me and my dad ( neither Porsche specialists by a long stretch ) have tried to breath life back into her but with no joy. What we do know is there is definately no spark at the HT leads but power to the coil.

Does anyone know if the stock alarm fitted by Porsche works by imobilsing the spark ? and if so can I disable / bypass it easily and how. ( and where the hell is it ? )

The car is fitted with an aftermarket imobiliser, but the device is wired to stop the starter motor from turning and is working as it should. As mentioned the alarm siren sounded when we refitted the battery, so this has to be the Porsche alarm as the aftermarket device has no siren. ( hope that's clear !



If the alarm is not to blame I did find a posting on another site regarding " Not starting with no spark " with a walk through guide, however it looks a bit indepth for me and might need some specialist tools ( specialist tools being anything other than a hammer, screwdriver and a wrench )

I also read that the DME relay can be problematic, I found a spare DME relay in the glove box, however I have no way of knowing if it was a working unit or faulty, tried swapping this but still the same.

Any suggestions would be very very very much appreciated, when I got back in the cabin last week the smell alone got me all nostalgic.

I'd really like to be driving her again soon.

Many thanks in advance.

Paul

Could be alarm or could be other electrical problem. Woun't be the DME because it doesn't play a part with the ignition system, only fuel.

Have you had a look at Clark's Garage guide. Pretty good for 944 things I've posted the link here http://www.clarks-garage.com
If you click on the Garage Shop Manual on the left; on the right is an alpha list and the Ignition System Troubleshooting is under I.

Hope this helps. Let us know how you go on.

DME is both ignition & fuel pump surely. But why keep a duff relay in your glove box?
Alarms are a pain. Don't have a Porsche one myself so can't help except if it's faulty you will need to rip it out & start again. You can bypass them direct from the battery to rule it out.
Hello 240z paul. Join the club it's worth every penny. Oh & let us know how you get on. When shes up & running we will want to see some pic's.

Hi

I have an after market meta alarm fitted to mine, i picked my car up last week and immediatley removed the battery and put it on charge (the battery is however the wrong one) When i re-connected it it did exactly the same thing...alarm sounded whilst the battery was off, but the battery back up pack which kicks in when the battery is removed was weak so only a little whistle could be heard.

When i re-connected the battery after charging it, the alarm sounded....deafening!!!!

I had a small key fob type thing..............i didnt know what it was for, also on the top of the windscreen was a small round device with a red light flashing on it, i pointed the fob at this and it turned the alarm off, i found out later that its a reset fob and receiver. Have a look around the cabin for something like this...the size of a 10 pence.

Dont know if this helps.

when you remove and refit the battery any alarm system that is connected to the car will instantly reset itself , even if you have not used the alarm for years. It is likely that the Porsche alarm system is currently in 'armed' state and will require either a programmed keyfob to disarm it or to remove the alarm altogether.

if you look under the carpet at the front of the passenger footwell you'll find a piece of ply which covers the car's ECU . The chances are that here is where the car's standard alarm was fitted as it links into the ECU which controls the cars fuel and ignition systems. Have a look and see what make is there.

I have seen the instructions somewhere on removing the alarm. maybe on the Clarkes Garage website in their workshop manual.

Remove the DME relay and check to see if you have 12v+ on terminal 30 of the relay socket. It should be constantly live and indirectly supplies the fuel pump .

I have knowledge of the T999 Meta Alarm so if you need any more info let me know.

this guide from Clarks garage on removing the alarm might be useful.
http://www.clarks-garage.com/pdf-manual/elect-23.pdf

Thanks for all the info guys, their seems a wealth of technical stuff available.

Can someone specify EXACTLY where the alarm module is found on my car !!

Had a look in both footwells and cant see anything like whats been described ( black box size of a ciggy packet )

Cheers

Paul

if its not in the pass footwell with the ECU then its not an original Porsche alarm but an aftermarket one. Probably under the bonnet or behind the ICE or under the dash could be anywhere. Are you sure its not a redundant immobiliser ? have a look around the cab and under the steering column for a small round hole where one may have been fitted

Have you checked if you have 12v+ at terminal 30 yet ? under the DME relay . Its a vital check and I can't help you further until I know

Hi guys

A quick update from the weekend.


Peanut I'll stick to this thread with any updates from now on cheers.

As mentioned before the car has power to coil but no spark.

Firstly, yes Peanut we have 12v+ on terminal 30 under the DME relay.

We found the ECU under the board in the passenger footwell and it seems the original alarm module has been taken out and replaced with an aftermarket unit, a thatcham 2 laserline model. Now the guy who had previously taken a look at the car said that the alarm unit was only wired up to disable the starter motor so I think we can rule out this alarm unit.

When the ignition is switched on should we be able to hear the fuel pump ? We couldn't hear anything even with the petrol cap removed.

Is there anyone with knowledge of the electrics on this model that would be willing to come and take a look, ideally someone with an S2 so we could swap the ECU and DME relay to eliminate them from the fault. Unlimited bacon sandwiches, a crate of beer and some moolah for your trouble.

I live in Chesterfield ( 5 mins from J29 of the M1 in North Wingfield )

All help much appreciated.

Many thanks

Paul

I'm too far away (even for money) but you need to get back to basics. I assume the rev-counter doesn't bounce? If not then it is DME, sensor or no 12V on the DME. Use a DVM & measure the DME plug from Pin 5 & 35, 18 & 5 you should have 12V across these points. This proves that the DME has power on it. Any issues here & you'll need to start following the path from the DME relay through. If possible swap the DME with another 944S2 as a test. If you have no spark then the fuel pump is irrelevant. If the DME has power & tests OK in another car then you need to test the TDC sensor with a scope or replace it with a good one.

Don't bother listening for the fuel pump ,the pump doesn't run on these cars with the ignition on.

When you first switch the ignition on the DME relay is momentarily energised and the pump runs for less than 1x second. then is switched off by the DME relay de-energising .(This is a safety feature which prevents your car catching fire in the event of a crash etc)

This allows the fuel pump to pressurize the fuel system to 2.5 Bar ready for starting.

The Motronic fuel injection and ignition system is very complicated and it would be pointless trying to explain how it works here.

Your best bet is to use a 3x way DME relay bypass which bypasses all the sensors which the ECU needs to see in order to allow the fuel and ignition system to run.

This will force your fuel pump to run continuously and will allow the ECU to pulse your ignition system.

Follow the Clarkes garage workshop manual guide for 'No start '. its the best there is .

Hey Paul,

I'm pretty much on your doorstep was having a potter about the lanes around Wingfield on Sunday in my old girl

I've got a spare dme relay that I know works and a running car to check both of yours if the 83 car relays are the same as the S2 one of the other guys will be able to confirm either way.

I'm away till Thursday but if it'll help give me a shout and I'll run over.

the 3x way bypass lead eliminates the DME relay completly. It replaces the DME relay and provides a permanant supply to the fuel pump and the ECU and ignition .
The fault is not likely to be the DME relay but if it is the bypass will confirm it .
Link 3x wires together with a spade connector on the end of each wire. Remove the DME relay .Put one spade in terminal 30 then put the other 2x spades into terminal 87 and 87b .
The pump should now run continuously. Crank the engine over and see if it fires. If not check for a spark

Paul I noticed this thread is still open and unfinished.

Did you ever find a solution ? it would be very helpful for other 944 owners that search the net and end up here to read the final solution