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1983 928 factory alarm?

 
Old 10-13-2016, 12:50 PM
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16vsilverstreak
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Default 1983 928 factory alarm?

US car. Did all '83s have a factory alarm? Today I started the car, I started to walk away while it warmed up and an alarm horn started going off. The horn seems to be mounted to right in the cowl area under or in the air box. I can't get eyes on it. There are no signs of an aftermarket alarm or a factory one. The car starts and runs while the alarm horn sounds. Thanks.
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Old 10-14-2016, 10:32 AM
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Wisconsin Joe
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Many did. If you put your VIN in the "Official VIN Check" thread, you can find out. They are not apparent to a casual visual inspection.

BUT...

The factory alarm includes a "disabler" that will prevent the car from starting if it's armed.
So if your car is running, and the alarm horns are going off, there's something odd going on.
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Old 10-14-2016, 04:05 PM
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I just revisited my 928 on 928oc.org WP0JB0927DS860412, it does indeed have the M533 Anti-Theft Device.
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Old 10-15-2016, 01:30 PM
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Alan
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The stock alarm horn is in the HVAC airflow enclosure.

The stock alarms should always disable the ignition when activated - so maybe that has been bypassed - but the alarm otherwise is still active. Or the alarm disable relay (in the alarm unit) is defective. Do you have a jumper between Z4 & Z6 on the CE panel - this would be an alarm bypass.

The alarm monitors the interior light tip switches and the door locks, hatch lock and the hood switch.

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Old 10-19-2016, 05:44 PM
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I've been searching threads on alarm bypass and ran across " Pull the Z-plug, and jumper Z-4 to Z-6 on the panel." and "83 and before are bridged Z1 to Z6. 84 is bridged Z1 to Z4" I do not have a jumper at the Z plug yet.

Just to clarify on an 83 US 928 on the Z plug you need to jump Z4 and Z6? I pulled the alarm module above the glove box, the car starts and the alarm horn stays quite but the volt meter stopped working.

I'm going to take the above Z4 to Z6 jumper as the correct jump. I will report back with my findings. Thanks for the help.
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Old 10-20-2016, 06:11 AM
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I've been working pretty extensively with 84 electrical for a while and therefore have had to dive into the alarm and the differences between years. And frankly, I learned the alarm jump protocol from alan, so let him review and confirm before you go forward.

Z4 to Z6 is for model year 84 only.

Z1 to Z6 works for 83 and earlier. The bridge needs to be there, otherwise the exciter circuit for the alternator will be interrupted. You can see that on the 83 electrical circuit diagram, Part I ( first page of the 83 diagrams ). Will try to post that below. If it doesn't show clearly, try clicking on the print preview in Word and that seems to sharpen the image or zooming a bit.

Separately, See the attached information snapshot from the CD set, specifically the 928 Electrical Training document, that talks about the alarm circuits between years and testing of them:
Attached Files
File Type: docx
84 alarm vs 83 and earlier.docx (570.4 KB, 57 views)
File Type: docx
83 wiring.docx (103.3 KB, 53 views)

Last edited by Landseer; 10-20-2016 at 08:51 AM.
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Old 10-20-2016, 01:41 PM
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Landseer, thank you for the verification. With the alarm module out I bridged Z1 to Z6. Turned the key to on and the voltmeter snapped to attention then I started the car. Problem resolved.
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Old 10-21-2016, 09:57 PM
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Excellent.
We Sullivan County guys need to stick together, btw.
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Old 10-22-2016, 02:35 AM
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You're in Sullivan County Tennessee? There's not many 928s around these parts.
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Old 10-22-2016, 11:33 AM
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Originally Posted by Landseer View Post
...

Z4 to Z6 is for model year 84 only.

Z1 to Z6 works for 83 and earlier.
You are of course quite correct - and I had forgotten the '83-'84 change.

The WD set I have on my computer is missing the '83 alarm details... There are normally few changes YTY on alarms so I referenced '84 - a mistake for this case.

Thanks for catching that - and glad the problem is solved for the OP

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Old 12-10-2018, 10:39 PM
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Originally Posted by Landseer View Post
Z4 to Z6 is for model year 84 only.

Z1 to Z6 works for 83 and earlier.
old topic, but wanted to say thank you and confirm that Z4 to Z6 worked on my 1984 928S
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