AVI_8
New member
I'm sure I've solved my problem but just thought I'd share it in order to prevent some head scratching if the same thing happens to you.
I hadn't started my 964 for a couple of months, due to work and weather it's been in the garage, went to start her today and though she turned over there was no life at all from the engine.
Took a plug lead off to check for a spark ... all ok there.
Thought it might be the DME relay so with the ignition on I removed it and slowly pushed it home, sure enough there was a click from it and from somewhere in the engine bay so I thought all was well and suspected the fuel pump.
It's a bit of a job getting to the pump but once I'd got to it and before I removed it I checked for power ..... There was none.
After a bit of head scratching I checked for power at the fuse (number 34) ... no power there, at this point I was suspecting my immobiliser was faulty then remembered I had a wiring diagram in an excellent book I have called Porsche Carrera 964 technical data without guesswork by Bently publications.
It showed that the DME relay has 2 contacts in it so I removed it and took off the cover then pushed it back in with the ignition on, sure enough only one of the contacts was closing and when I manually held in the other contact the fuel pump started working ..... Big sigh of relief, I'm hoping that a new relay will solve the problem.
I just wanted to point out that in order to diagnose a DME relay failure you have to see both contacts move when the covers off.
Also I noticed that if I was ever away from home and had a relay failure and broke down it would be possible to physically hold the contacts together using a matchstick or something similar as a temporary repair until I got the car home again. I tried this using a small piece of balsa wood and the car fired up straight away.
Regards
I hadn't started my 964 for a couple of months, due to work and weather it's been in the garage, went to start her today and though she turned over there was no life at all from the engine.
Took a plug lead off to check for a spark ... all ok there.
Thought it might be the DME relay so with the ignition on I removed it and slowly pushed it home, sure enough there was a click from it and from somewhere in the engine bay so I thought all was well and suspected the fuel pump.
It's a bit of a job getting to the pump but once I'd got to it and before I removed it I checked for power ..... There was none.
After a bit of head scratching I checked for power at the fuse (number 34) ... no power there, at this point I was suspecting my immobiliser was faulty then remembered I had a wiring diagram in an excellent book I have called Porsche Carrera 964 technical data without guesswork by Bently publications.
It showed that the DME relay has 2 contacts in it so I removed it and took off the cover then pushed it back in with the ignition on, sure enough only one of the contacts was closing and when I manually held in the other contact the fuel pump started working ..... Big sigh of relief, I'm hoping that a new relay will solve the problem.
I just wanted to point out that in order to diagnose a DME relay failure you have to see both contacts move when the covers off.
Also I noticed that if I was ever away from home and had a relay failure and broke down it would be possible to physically hold the contacts together using a matchstick or something similar as a temporary repair until I got the car home again. I tried this using a small piece of balsa wood and the car fired up straight away.
Regards
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