964 Starting Woes - DME? Alarm? Ignition Switch? Ghosts?

[Mike D'Silva]

I have a real love/hate relationship with this stupid car. Yes you can tell at the moment I am on the 'hate' swing of the scale at the moment.

Went to start it, and normally it cranks for a half second and fires, EVERY TIME. But not now. Cranks and won't fire. 

So I think DME relay, which is weird since I put a new one in last year.. I put my little 3 pin jumper in and the car fires up perfect. So, it MUST be the DME relay right?

I order a new one, it turns up, plug it in and it's no different.. cranks and won't start. So I find this article on PP about the 993 relay and trouble shooting.. part of the test, says pin 30 should have 12V all the time, and mine does. 

Then with the key ON, pin 86 should have voltage too (it doesnt say 12V but in the accompanying photo in the article, it shows 12V).  Mine shows 1.3 volts.. and sometimes, 3V.. why doesn't it show 12v?

https://www.pelicanparts.com/techarticles/Porsche-993/19-ELEC-DME_Relay_Troubleshooting/19-ELEC-DME_Relay_Troubleshooting.htm

More wasted time on the web (watching a few cat videos of course) and no voltage to pin 86 seems to suggest either alarm woes, or ignition switch dodgy. I cannot find the alarm module.. I think it has an alarm since I set it off once, but I pulled both seats (I hate that job) and the only modules underneath are DME under left seat, and something about cruise control or spoiler or central locking under the other seat. I forget the part numbers but I don't think they were alarm.

So, I'm kinda hoping ignition switch; 

Any thoughts??

 

[KGB]

I have a red one, it’s starts every time.

Auto lecky, I reckon.  

Glad to have been of assistance.

[MartinE]

My 964 has an after market Dynamco alarm. There are several relays installed under the fuse box in the frunk and the alarm module is under the dash. I often wondered what would be the outcome of one of the alarm relays failing.  I suspect the car won't start.

Good luck.

[Mike D'Silva]

I just ordered a new ignition switch, however I have a feeling this thread might be onto something too..

https://rennlist.com/forums/964-forum/339453-porsche-alarm-module-where-is-it-on-a-90-c4.html

[BlitzKonig]

Have you tried measuring the Output on Pin 18 (Terminal 30) of the ECU? To ensure you are actually get the 12V you expect?

Also might be worth checking this if you havent already done so.

[Country 964]

On 5/9/2018 at 5:58 PM, Mike D'Silva said:

I cannot find the alarm module.. I think it has an alarm since I set it off once, but I pulled both seats (I hate that job) and the only modules underneath are DME under left seat, and something about cruise control or spoiler or central locking under the other seat.

Alarm control unit = 928 618 260 00, for MY91-. Part was superseded to ....03.

From memory, it's under the driver's seat and connects to the central locking control box, since that's how it gets armed/disarmed.

[Mike D'Silva]

thanks for the reply.. my alarm module is in the front compartment, on the passenger side of the car, tucked right up under the bonnet hinge.. impossible to get to.

Thankfully, my new ignition switch has fixed my issue.

[9elf]

Sounds like you have solved the problem but if you ever need to try another DME relay, just let me know. I am in Brisbane and carry a spare.

Craig.

[Mike D'Silva]

5 minutes ago, 9elf said:

Sounds like you have solved the problem but if you ever need to try another DME relay, just let me know. I am in Brisbane and carry a spare.

Craig.

Thanks Craig... I bought 2 new ones before I bought the ignition switch! Are you heading to Coorparoo tomorrow?

[9elf]

No. Have to work unfortunately.