[marazas]

I have original alarm in my car #928 618 260 01 and I wonder if it has immobilizer functions and is where are those connections?

The alarm itself is a pure crap as it disarms when unlocking the door and in our cars it can be done with almost anything. I have had my car stolen and got it back and want to install better alarm.

I would maybe need to remove the original alarm unit or maybe I could use it connections for fuel pump (if it has immobilizer) and I am looking for wiring diagram. Any help is appreciated!!!

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[DaveN]

You can get the manual here http://www.cannell.co.uk/968_Workshop_Ma...8WRKSP.pdf
It has the wiring diagrams and as far as I can tell it's free. I doubt Porsche condones this though [img]style_emoticons/<#EMO_DIR#>/smile.gif[/img]

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[PorscheDude]

Dave that is a great resource. I'm surprised it's been up as long as it has.
Just a word of caution guys, please send that link around via PM just in case.

Sorry OP, I can't offer any advice with your problem.

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[marazas]

Thanks! I will check it again... Does anyone know some way to see if my model have connected immobilizer functions?

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[marazas]

After looking at the wiring diagrams I see that alarm unit has connections to a number of swithes such as: Glove compartment contact, speedo signal. What does it do with them? Can they be used to trigger alarm (they did not do that in my test)?

How is anti-drive off feature connected? Does it cut off connection between ignition lock and starter or is it something more advanced? I could use it for my new alarm unit.

Would be great if anyone could enlighten me on those matters...

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[wildcat]

I also have an original alarm and it seems to be working fine but I was curious too as the manual states "car alarm immobilizer" and I wondered exactly what that function was. My 968 is a '93 which is a cut off date for later models for certain components I discovered searching for parts. Any info on this "immobilizer" function would be useful.

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[flash]

i have yet to run into an immobilizer. the closest thing has been the stereo locking you out. that being said, the manual clearly states that it has an ignition immobilizer, which would prevent starting the car until you shut off the alarm. this would likely be either in the alarm unit itself, or more likely in the ECU. in either case, you cannot delete the ECU, so if it's there, you are stuck with it. if you delete the alarm, it may engage the circuit if in the ECU. i know that's how i would set it up if i were laying out the logic.

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[wildcat]

Thanks for your input. I wondered if the alarm would allow the engine to crank over but restrict the DME from sending an ignition pulse. This now seems unlikely, but the old idea of clipping the ignition wire from a car sparked the notion (pun there?). Would seem silly but the wiring diagram does not explain what goes on inside the alarm box. I have since ruled that out as the culprit.

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[flash]

it probably wouldn't mess with the ignition pulse. it would probably cut the power to the DME relay, which engages the fuel pump and the ECU.

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[wildcat]

I agree that would be more logical. The DME relay was replaced and I was looking for another possibility... alas it was the DME itself which has been sent for repair.

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[flash]

i wouldn't assume that the new DME relay worked. they have been known to be bad out of the box. there are instructions here somewhere for a jumper, which would eliminate that as a possibility.



have you checked the DME relay fuse?

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[wildcat]

My wording was inadequate as I did not elaborate on what I meant by "replaced". I pulled the relay to check the power in the relay slots. Then I put the old style relay in the slot and could hear the mechanical relay engage. Only one engages in Ignition On the other apparently engages in "starter mode". I also have a new style which is transistor based and you can't tell what its doing. But the voltage is there and if the alarm does immobilize in the fashion you mention, then its not the alarm. I did check the DME fuse. There are three relays associated with the DME and Alarm ( they are placed behind both) which are not mentioned in the owner's manual of my '93, if you happen to know what they do I'd be most interested, TIA.

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[Davbert55]

I'm stripping my car for track use.  I ran across this post yesterday trying to determine what, if anything, would happen with the alarm ECU removed.  i sort of expected the car wouldn't start.  it didn't.  i had to jumper pins I/4 and i/6 to bypass a control relay that powers part of the DME circuitry.  Interestingly enough, this ECU gets its power (12VDC with ignition switch on) from the airbag ECU.  I removed the airbags and computer as part of the conversion to track use only.  One needs to jumper pins 11 and 12 in plug number 1 to supply power to the Alarm connector.  If you're troubleshooting a no start condition and you have fuel (i smelled plenty of fuel when attempting to start), look at these disabling features as a possible culprit.

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