C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

1987 alarm problem

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Old Aug 10, 2011 | 01:51 PM
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Default 1987 alarm problem

When I lock the doors with the power lock and then shut the door the alarm goes off immediately. It used to be intermittent in that the alarm would go off after a few minutes but now it is immediate. I thought that maybe the switches that push in when the door shuts were bad but I tested them and they are fine. Same for the switch on the hatch.

Related to this is the door ajar light. Neither door will will turn the light on. I checked the bulb and it is fine.

Do I have a bad theft deterrent module? Where is this module located?
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Old Aug 10, 2011 | 03:22 PM
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Have you tested the clk/ctsy fuse ?
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Old Aug 10, 2011 | 03:24 PM
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http://members.shaw.ca/dankai/Vats%20Electrical.pdf

http://members.shaw.ca/dankai/Interior%20Lights.pdf
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Old Aug 10, 2011 | 04:53 PM
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Default 1987 alarm problem

I checked the clk/ctsy fuse and it works fine. I looked at the pdf links that agent 86 sent. I would like to check the theft deterrent controller/connector but I do not know where it is located.
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Old Aug 10, 2011 | 05:02 PM
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You have to pull the dash pad (not horrible) then remove the bread-box to access the theft module.
In some cars its accessable thru the center display but I'm pretty sure the 87 is mounted more in the middle of the bread box. Once the dash pad is off, look for the most difficult thing on the passenger side dash to get to....that'll be your theft module.
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Old Aug 10, 2011 | 09:04 PM
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When there are multiple problems in a common area (door) I would suspect a ground issue.
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Old Aug 10, 2011 | 09:36 PM
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I lubed the door ajar switches so now the door ajar light comes on as it should. But the alarm still goes off when I arm it and close the door.
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Old Aug 11, 2011 | 09:50 AM
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The theft deterrent controller is near ECM. You have to remove the passenger foot-well panel(has a courtesy light), then slide in on your back.

Do your courtesy lights work when you turn the headlight switch fully counterclockwise ?



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Old Aug 11, 2011 | 10:12 AM
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Yes the courtesy lights turn on when the headlight switch is turned fully counterclockwise.
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Old Aug 11, 2011 | 12:40 PM
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How did you test the door jam switches ?
Seems to me that the switches are associated to both your problems.
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Old Aug 11, 2011 | 01:41 PM
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I tested the switches as follows.

With the car ignition on I opened the car door.
1. I pushed the switches located by the door hinge area (the front) in and out. The courtesy lights went on(when not pushed) and off(when pushed).
2. I pushed the switches located on the opposite end (the rear) of the door in and out. The door ajar light went on(when not pushed) and off (when pushed).
3. I opened the rear hatch and the hatch open light went on. I closed the hatch and the hatch open light went off.
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Old Aug 11, 2011 | 03:15 PM
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Originally Posted by William999
I tested the switches as follows.

With the car ignition on I opened the car door.
1. I pushed the switches located by the door hinge area (the front) in and out. The courtesy lights went on(when not pushed) and off(when pushed).
2. I pushed the switches located on the opposite end (the rear) of the door in and out. The door ajar light went on(when not pushed) and off (when pushed).
3. I opened the rear hatch and the hatch open light went on. I closed the hatch and the hatch open light went off.
Doh !! I reread your first post. This comment "Neither door will will turn the light on. I checked the bulb and it is fine." is what threw me off. I thought you were talking about the courtesy lights. Now I see you were talking about the door ajar light.

Three years of grade 2 and I still can't read.

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