Porsche Repair: Resetting computer, gadgets and gizmos, time delay relay

Question
When I get out of my 1999 Boxster I can lock the door, most times the lights will flash twice, bot 60% of the time the horn does not beep. Therefore, when I go to get back into the car and when I crank the car the flasers blink. I must than relock the car and try again. Any Ideas?

Answer
Hi John,

I am always impressed by the gadgets and gizmos coming out on the newer cars, the convenience factor is amazing.  However, the Yankee in me says every new bit and byte is one more maintenance step or possible repair in the future.  The problem you're having is one of the examples why I am SO happy working on my little (very simple and rustic) Porsche made 50 years ago!

I wouldn't be too quick to assume the computer needs resetting.  You could easily try this though by disconnecting the battery terminals and waiting the presrcibed time...some cars like 5 minutes, some cars like 15 minutes.  Once you reconnect the batery (ground terminal connected last) the computer will be reset and hopefully be happy.

One other possiblity to consider is this.  There are more and more applications where manufacturers are using relays to trigger selective and specific activities.  For example, using your description, let's say the 12v signal that creates your flashing security lights also goes to a time delay relay that activates a split sceond later and is supposed to cause the horn to sound, and that signal in turn goes to another relay which causes the lights to flash again.  If the horn relay (not THE horn relay, the one that activates when you hit the horn button...another one) is faulty, the string of proper sequences is broken...and I don't know what re-locking the car does but it sounds like it's working for you.

If I had a wiring diagram I could verify this possibility, but the diagrams for the newest cars are harder and harder to get for some reason.  The owners manual might show the location of a relay such as I've described...the relay can be checked before you replace it...or depending on its price, you might just buy it, replace it and see what happens.

There are likely other reasons for your problem, but I think this is the most probable.  Please don't hestitate to write me a follow-up note for clarification or to let me know what you found.

Dave