docwyte

OK, here's a little Alarm ECU 101. There are actually three different alarm ECU's that Porsche used. The early cars got 911.637.104.00, the Clark's Garage bypass procedure works for cars with this ECU. Then the "Middle" cars ('87-'88?) cars got 911.637.104.02. Both of these plugs on the cars body side are white. Sometime in 1989 Porsche switched to the "Late" Alarm, which has a blue plug and the part # starts with 928.

My car is a 1989, but didn't have the blue body plug and the 928 part # alarm ECU didn't plug into my car. The Clarks Garage bypass procedure DOES NOT work on the Late cars! It should work on the "Early" and "Middle" cars but check the wiring colors against what my car had and what Clarks Garage says they should be. If they match Clark's Garage, use it, if not, use my procedure.

Additionally you need to match the 911 part # alarm ECU with a 944 part # alarm relay, while the 928 Alarm ECU gets a 928 Alarm relay part #.

Ok, here's where Porsche started F'ing with me again. So even though my car is an 1989 and had the white plug Alarm ECU harness, it STILL didn't have wiring to match the 1987-1988 cars like the Part # 911 Alarm ECU has.

So that meant that even though the Alarm ECU plugged in, it still wasn't working. I couldn't open my rear hatch with the key and the alarm and relay were clicking away madly.

Sigh. Time to do some more research on how to properly bypass the alarm in the 1989's. A little while later I had a procedure that was supposed to work. Guess I'll either burn up my wiring harness or it'll finally work!

So I went out and did it and it WORKED! Holy crap. I can finally open my rear hatch with the key from the outside!

Ok, so what did I do?

Well, first off you need to make two jumper wires with male spade connectors on each end. Now go unplug the alarm ECU. There are two plugs, one large 8 wire one, one small two wire one. On the large 8 wire plug, jump the black with red stripe wire to the green wire, which should be jumping pins #1 to #3.



Now go to the fusebox and find relay G19, which is the alarm bridge relay and remove it. You need to jump pins 4 to 5 in it. According to what I read, this was the red wire to the red/black wire, but on my car it was the red wire to the red/blue wire.





You're done! Dance a jig now that you've FINALLY gotten rid of the damn OEM alarm!

mtnman82

Been following you r alarm adventure with great interest. I have a p.o.s old aftermarket alarm installed from previous owner along with the factory. I've looked at removing it a couple times and wound up running away... Thank you very much for posting your solution!!!

odurandina

THANKS A TRILLION DOC !!

now Amber Lamps can proceed with zero uncertainty and get that Godawful thing out of here.

damn thing might even start after.

Amber Gramps

Sorry, info belongs in the other thread.

Raudel

How do I get to the alarm module itself?

hally

Thanks! My 89 has the 928 part number

alex

So OD or anyone else- is this confirmed to work on the 968 alarms with 928 part number?

docwyte

Chances are it will but I never tested it on a 968 so can't say for sure.

alex

Thanks doc... Hopefully I'll have an answer one way or another pretty soon.

alex

Looks like the 968 has a significantly more integrated alarm. After looking through the wiring diagrams for a while, and not wanting to chance losing the myriad systems it is tied into (I still want the keyless entry to work, etc), I decided to try just snipping the "alarm system prime" (aka arm or turn on) #1 wire on the #II connector (yellow). However, while it does keep the factory alarm from turning on, it kills the automatic locks, so will need to get more involved. Probably needs it's own thread.