Can I disconnect the security system?

[Tim Boyer]

Hi,
My alarm goes off randomly and as a result drains the battery. I know that this is a common problem with these cars. Any suggestions on how to fix it or disconnect it?
Thanks,
Tim

[JK McDonald]

Hey Tim - There are a couple of versions of the alarm disable procedure - what year 928 are we talking about. The earlier cars up to 1984 are considered one major group and the 1985 and later cars are different.

Michael

[Tim Boyer]

1984

[JK McDonald]

Hey Tim - I'd tried to revive the alarm system on Miss Purdy years ago - but finally gave up after almost being stranded a couple of times. The source of my problems were from erratic safety switch contacts through out the car (key locks, hood, rear hatch and especially the door switches). All these parts can be cleaned and/or replaced but it's a pretty major project. By the way a faulty door switch + an interior courtesy light is also known to drain your battery.

Assuming you have a 1984 U.S. version 928 (other years in this early group still have the "Z Plug" but are jumpered differently) and not a European model - you need to find the black "Z Electrical Plug" in the lower center of the Fuse/Relay electrical panel. Wiggle the "Z Plug" until it pulls off it's 6 electrical terminals. Using a short jumper wire with two female electrical lugs - connect terminal Z4 to Z6 (#4 is Bottom Right and #6 is Upper Right). On my car I simply wrapped the the loose black "Z Plug" with electrical tape and secured it with zip ties. Here are a couple of excellent photos from a Pelican Parts Member - Landseer.

Don't forget to write up what you did in your maintenance log book - there is an old Chinese saying "The Faintest Ink is Far Better Than The Best Memory".

Good Luck - Michael

[JK McDonald]

Hey Tim - Were you able to locate your car's "Z Electrical Plug" and jumper the #4 - #6 terminals ? On Miss Purdy - once I'd installed this jumper all of my intermittent alarm problems were eliminated.

Good Luck - Michael

[Tim Boyer]

Still looking for ZElectrical plug. On the picture there are two yellow lines . Is the plug at one of them or both of them!
Thank you for you help!
Tim

[JK McDonald]

Hey Tim - The electrical plugs are color coded. They all have 8 wire terminals and the same height EXCEPT the shorter 6 terminal "Y" and "Z" plugs located in the lower center of the Relay/Fuse electrical panel. The "Z Plug" is black and found to the right side of the empty "Y Plug".

The lower yellow arrow points to the (now) disconnected wiring harness half of the "Z Plug" laying on the passenger floorboard. The upper yellow arrow points to the location of the 2nd half of the "Z Plug" where the disconnected portion plugs into the Relay/Fuse panel.

You will need to make-up a short jumper wire with a female electrical terminal lug on each end. Now - with the two halves of the "Z Plug" seperated - your jumper wire is installed on the upper half of the "Z Plug" onto the #4 and #6 male terminals. (Lower photo is a close-up of the Relay/Fuse Panel side of the "Z Plug" with Jumper in place). This will eliminate the alarm system on a U.S. 1984 Porsche 928..

Good Luck- Michael

[JK McDonald]

Hey Tim - How did your "Alarm Deactivate Smoke Test Go" ?

Better - Worse - About The Same

Michael

[Tim Boyer]

Hi,
I tried to respond earlier but for some reason it did not post. Anyway, i had back surgery in June so I am not able to get to this project right now. It is driving me crazy not to be able to tackle some of these projects. When I first came home from the hospital the alarm was going off at different times of the day and night. It would ring for about 30-60 seconds and then stop. That is when I decided to ask for some direction. Ironically, the alarm has been silent for the past few weeks.
As soon as I can I am going to try out your recommendations and I will post the results.
Thanks for your insight into this anomaly of the 928!
Tim

[JK McDonald]

Hey Tim - Whenever I hear about someone having intermittent car alarm problems I can't help but remember a book written by a prolific California car thief. Although now retired (in prison), this guy specialized in stealing high end cars for shipment to the overseas black market. The movie "Gone In 60 Seconds" with Nicolas Cage was (Very Losely) based on his techniques. One of the simplest and most successful methods he used was to repeatedly trip an ultra complex alarm until the irritated owner would shut the suspected faulty system off.

I'm not sure if the 928 Porsche was ever on this guys hit list but Tim, next time the alarm goes off - watch out.....

Hope Your Back Gets To Feeling Better - Michael