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theft deterrent system

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Old Sep 29, 2016 | 11:55 PM
  #1  
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lofti5
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Default theft deterrent system

I have a 89 c4
my problem is power door locks work when doors are open,
with or without car running, keys in or out of ignition. As soon as i close a door they stop working, I had a post say it might be "forced entry mod".
Does anybody else have any ideas
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Old Sep 30, 2016 | 06:07 AM
  #2  
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I don't have an 89 so anything I offer is purely a guess but here it goes.

Does the car have an aftermarket alarm?

When did this problem start? Was it after some other work was done to the car?

I would disconnect the door pins (switches on the door that tell the car the door is shut or open) and see if that changes the symptoms. If it does then you know the door pins are related to the problem. If not then you know the issue is further in i.e. pinched wires in the door or aftermarket switches somewhere else.

It may be possible that a previous owner messed with the wiring in some manner to link the power feeding the door locks to say, the interior lighting power. So when the doors are open and the lights are on, then the door locks have power. When the doors are shut, then the power is removed.

Again, I do not have an 89 and I don't know what has been done to your car in the past. With some additional information we (the forum) may be able to help you narrow down your problem though.

Good luck!
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Old Sep 30, 2016 | 07:54 AM
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Originally Posted by kg4fku
I don't have an 89 so anything I offer is purely a guess but here it goes.

Does the car have an aftermarket alarm?

When did this problem start? Was it after some other work was done to the car?

I would disconnect the door pins (switches on the door that tell the car the door is shut or open) and see if that changes the symptoms. If it does then you know the door pins are related to the problem. If not then you know the issue is further in i.e. pinched wires in the door or aftermarket switches somewhere else.

It may be possible that a previous owner messed with the wiring in some manner to link the power feeding the door locks to say, the interior lighting power. So when the doors are open and the lights are on, then the door locks have power. When the doors are shut, then the power is removed.

Again, I do not have an 89 and I don't know what has been done to your car in the past. With some additional information we (the forum) may be able to help you narrow down your problem though.

Good luck!

It sounds like the power source was changed from live all the time to some form of switched source based on the description provided.
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Old Sep 30, 2016 | 10:13 PM
  #4  
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lofti5
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From: La Crescenta CA
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Originally Posted by kg4fku
I don't have an 89 so anything I offer is purely a guess but here it goes.

Does the car have an aftermarket alarm?

When did this problem start? Was it after some other work was done to the car?

I would disconnect the door pins (switches on the door that tell the car the door is shut or open) and see if that changes the symptoms. If it does then you know the door pins are related to the problem. If not then you know the issue is further in i.e. pinched wires in the door or aftermarket switches somewhere else.

It may be possible that a previous owner messed with the wiring in some manner to link the power feeding the door locks to say, the interior lighting power. So when the doors are open and the lights are on, then the door locks have power. When the doors are shut, then the power is removed.

Again, I do not have an 89 and I don't know what has been done to your car in the past. With some additional information we (the forum) may be able to help you narrow down your problem though.

Good luck!
We inherited the car from my wifes grandfather who bought it new in '89. It has about 128k miles and had been sitting in storage for about 6 years after he blew the head gasket. We fixed that and now are going down the list of repairs for a car that has been sitting. It also had a bit of a mice infestation.

As far as I can tell everything is original. I have already replaced all acuators and door switches. Checked all wires for damage (from the above mentioned mice) but can find no reason for them not to work when the doors are closed.

I will try disconnecting the door pins. Someone suggested that it may be due to the forced entry system. I found the module but other than replacing it, I not sure how to check if thats the problem
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Old Sep 30, 2016 | 10:15 PM
  #5  
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lofti5
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From: La Crescenta CA
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Originally Posted by hcbph

It sounds like the power source was changed from live all the time to some form of switched source based on the description provided.
its all original
nothing added nothing changed
i chased the wiring diagram with the gm manual and can't find a break
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Old Sep 30, 2016 | 11:35 PM
  #6  
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Cliff Harris
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From: Anaheim CA
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TDS (Theft Deterrent System) is what honks the horn if a door is opened while it's armed. It has NOTHING to do with VATS and they are not connected in any way.

SECURITY light flashing: door is open, system is NOT armed.
SECURITY light not flashing (on solid): door is open, system IS armed.
The SECURITY light will go off if the door is closed or the ignition is turned on.
You disarm the TDS system by unlocking the door. Make sure to turn the lock as far as possible and return the key to the vertical position before withdrawing it.
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