Alarm Goes Off Immediately - Mid Restoration - What Happened?

suprarx7nut

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I'm mid-restoration on my 91. Totally stock car, totally disassembled from the dash rearward. Totally intact from the firewall forward. No door locks installed, no door sensors, no door harnesses plugged in, basically just the unibody, dash and seats. Engine and drivetrain totally untouched.

I've moved it in and out of my garage dozens of times in its current state.

Battery was DEAD today. 3.5V. It'll get replaced later, but something else is going on.

I went to charge up the battery and as soon as I got the charger connected, it started wailing the alarm. Key in ignition, turn to on, alarm went off. Starter will not crank. Seems the alarm has disabled the starter and I can't reset it.

I disconnected the battery and let it charge completely. The instant the battery cable touches the battery post, the alarm goes off and deafens my ears.

WTF? Anyone have a clue what suddenly triggered the alarm and how I might disable it to get this car shuffled around in my driveway? Cutting wires is not an option here.
 

Piratetip

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I have to figure this out as well.
If I do not lock the doors from the inside and do the pull handle close door from the outside, the car alarm has issues.
If I don't lock and close the door, there is a 50% chance the alarm just goes off without even touching the car.
It's done it in my driveway, the gas station, today at the store. Pretty annoying, a sensor is triggering it but don't know what.

The vehicle won't crank after this unless I unlock go in, turn ignition ON then OFF.
Then do the lock vehicle procedure, unlock again.
After that the car is fine.
 

Piratetip

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Can you just pull the immobilizer until you get everything else installed to the vehicle?
 

suprarx7nut

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Can you just pull the immobilizer until you get everything else installed to the vehicle?
I could, I suppose, but my understanding (perhaps totally wrong) was that bypassing the immobilizer involved splicing together wiring. Since I refuse to cut and splice wiring if poosible on this build, it would take some time to pull terminals out of connectors and make new plugs to bypass needed circuits. Might as well just start installing sensors and locks again at that point.

I hope I'm wrong though. It would be great if u could just unplug the alarm ecu and start her up.
 

A70nut

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My dads 87 did this when pulled apart from paint. You need to install the driver door lock assembly and turn the key in the cylinder and then open the door by the handle to get the car to stop freaking out as best I can understand what happened to it.
 

3p141592654

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Yes, there are several switches in the door.

The key locks have two leads to arm (BR-Y) and disarm (V-Y) that are grounded to actuate. These are shared between both doors. You need to ground V-Y to disarm the alarm. This must happen before the door is opened. Pins 3 and 11 of ECU.

Door open switch. This is in the latch of each door (its not the dome light switch) . Signal the door is open or closed. An open door with the alarm armed will trigger the alarm. The line is grounded when the door is open. Pin 7 (P-B) of the ECU. Shared for both doors.

Door locked switch. This is in the lock solenoid. I think grounded when locked. Not sure on that. Pin 8 (L) of ECU. Shared for both doors.

Once the alarm is triggered, it takes some work to shut it up.
To disarm you are going to need to apply 12V to pin 4 (that is what happens when you turn on the ignition switch). Then you need to ground the disarm signal. That should shut it up. YOu may also have to ground the door open signal after disarming.

Flaky alarms are usually because the door open switch in the latch is not working well or the door lock solenoid switches are not working well.
 
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suprarx7nut

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Yes, there are several switches in the door.

The key locks have two leads to arm (BR-Y) and disarm (V-Y) that are grounded to actuate. These are shared between both doors. You need to ground V-Y to disarm the alarm. This must happen before the door is opened. Pins 3 and 11 of ECU.

Door open switch. This is in the latch of each door (its not the dome light switch) . Signal the door is open or closed. An open door with the alarm armed will trigger the alarm. The line is grounded when the door is open. Pin 7 (P-B) of the ECU. Shared for both doors.

Door locked switch. This is in the lock solenoid. I think grounded when locked. Not sure on that. Pin 8 (L) of ECU. Shared for both doors.

Once the alarm is triggered, it takes some work to shut it up.
To disarm you are going to need to apply 12V to pin 4 (that is what happens when you turn on the ignition switch). Then you need to ground the disarm signal. That should shut it up. YOu may also have to ground the door open signal after disarming.

Flaky alarms are usually because the door open switch in the latch is not working well or the door lock solenoid switches are not working well.
Ok, you sir, need to let me know if you're ever in the Denver area. You've got any drink you like on my dime. You saved me an entire night of parts hunting and assembly.

All I had to do was ground the pin 3 node. There was a connector available in the kick panel of the passenger foot well (connector P2). I had a 6" length of wire with a female terminal on it in my toolbox, plugged it into that bare male terminal, touched ground, and could hear the alarm ECU click.

It fired right up after that.

Can't thank you enough. Please let me know if I can return the favor and have yourself an awesome St Patty's Quarantine day!

-Andy
 

3p141592654

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Glad I could help. I had to do a deep dive into the alarm many years ago when I installed a more modern Viper on top of it. Was in Denver a few months ago, but with travel all but halted I'll have to take a rain check for now.
 

debrucer

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Glad I could help. I had to do a deep dive into the alarm many years ago when I installed a more modern Viper on top of it. Was in Denver a few months ago, but with travel all but halted I'll have to take a rain check for now.
Well then, if you’re ever in San Diego then I’ll buy the drink :). Great answer! And I suspect I’ll need the info when I finally get there :).
 
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