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alarmsystem on a '84 vette

J

johnny

Guest
does anybody know if there is a alarmsystem on a '84 vette?? And when there is one, how does it works?

John.
 

Ken

Gone but not forgotten
Joined
Jan 30, 2001
Messages
8,236
Location
Hermosa Beach, CA
Corvette
1987 Z51 Silver Coupe
From the GM Corvette Service Manual
Protective Switches
The doors and rear hatch are equipped with protective switches which will trigger the alarm, if opened while the system is in the armed condition. The switches are located in both door hinge pillars and at the hatch opening. Each door lock is equipped with a tamper switch which will trigger the alarm if the lock cylinder is tampered with in any way different from the normal mode of operation.

System Fusing
The Electronic Theft Deterrent System (UTD) is electrically protected by a 10 amp fuse.

Controller
The controller is all electronic and is serviced on an exchange basis. The controller operates in two stages; first is the “Armed” stage, and the second is the “Activated” stage. These stages will be explained separately.

Arming
After the ignition is turned off, the system may be armed at either opened door by:

  • [1.] With power door locks: Activating the electric door lock switch to the lock position.
    [2.] With manual door locks: Depressing the door lock button to the lock position. When the last door is closed, (after a 5 second delay) the system arms.

Disarming
The system is disarmed by unlocking the driver's door with the key or by turning the ignition on. Alarm shut down is accomplished only by unlocking the door with the key. If the driver wants to prevent arming the system after using the “Door Lock” rocker switch, the switch can be moved to the unlock position before closing all doors. He may also cancel the arming process by rotating the ignition switch to the "ON" position, then back to lock. Rotating the ignition switch will not cancel the alarm once it is activated. The doors may be locked mechanically using the door key without arming the system. The ignition key in the ignition lock can only disarm the system, (before the alarm is activated).

Automatic Shut Down
Once the alarm has been activated, alarm will continue to operate for a period of three-seven minutes. At the end of the time out period, the alarm will automatically shut off to conserve battery power and, if the locks have not been damaged, the system will rearm itself. However, once the system has been activated, the starter interrupt relay will remain energized until the proper disarming sequence is initiated.

VATS SYSTEM
VATS uses a special ignition key which allows the VATS module to:

  • [1.] Signal the ECM.
    [2.] Close the starter circuit.
Without a signal response from the VATS module, the ECM will not allow fuel injection. VATS protection is present even after the present alarm system is defeated, or if the car is left unlocked. Use of the VATS system requires no changes in operation (arm-disarm) over the 1985 system.

VATS SYSTEM OPERATION
The VATS system operates to prevent starting (cranking) of the vehicle, and fuel delivery to the engine, using any key other than the special electrically coded ignition keys supplied with the vehicle at new car delivery. The VATS system operates independently of the present UTD alarm system. The system is completely passive and requires no active involvement from the operator to function. When the operator turns the ignition “OFF”, cranking and engine fuel delivery are automatically disabled. Inserting the properly encoded key into the ignition signals the VATS module to permit cranking and fuel delivery to the engine. If the key used does not have the proper electrical coding (unauthoized starting), the VATS module will reset for 2 to 4 minutes (crank and fuel disabled) and will not permit starting during this period even with the proper key. To start the vehicle, the key must have the correct mechanical and electrical coding. The ignition lock cylinder contains electrical contacts used to "read" the ignition key.

KEY REPLACEMENT
If the ignition key is lost and the mechanical code is unknown, the mechanical code must be determined using current key replacement procedures. The mechanical code must be cut on a blank designed for use with the VATS system. The key must be electrically coded to match the code of that particular VATS equipped vehicle. Electrical coding requires two steps. A special decoding tool is used to determine the code required, the proper code is then programmed into the key.

The preceeding was taken from the 1987 service manual, from another source, this indicates the system came out in '86.
PASS-Key Theft-Deterrent System
Corvette pioneered the use of PASS-Key, originally known as VATS (Vehicle Anti-Theft System) on Chevrolet passenger cars. The system, introduced in 1986, relied on a pellet embedded in the ignition key. If an improper key was used, the system cut off the starter and the fuel injectors, immobilizing the Corvette. The VATS system is credited with reducing Corvette thefts by 45 percent in the first year alone. Theft-deterrent systems are common among many Chevrolet passenger cars today, including a new system called PASSLock on some Chevrolets, that offers similar protection without the need for a key-mounted resistor pellet.
 
J

johnny

Guest
thanks Ken your very helpfull

It for my friend, who has a 1984. He got stuc in the city, when he opend his car from the inside...

At least everybody knows that he have a vette!


John.
johnnyvette.jpg
 
E

Eagle85C4

Guest
Hey...thank you for the info...I have set it off a few times and had to open the hood and unplug the horns...till it stopped. It would appear someone before me has wired around the starter relay. Under the hood near the brake booster the bundle of wires has been opened and the purple wire was cut and a red wire was connected to it and run back under the dash to +12 off the ignition switch. Some day I plan to reconnect the wiring like it should be. Thanks again...
 

vms4evr

Well-known member
Joined
Jul 18, 2001
Messages
466
Location
Durham, NC
Corvette
2002 Flat Black Z06
On my92 I had a problem where unlocking the door would sometimes set off the alarm and/or disable the starter.
I ended getting my freind to install a keyless entry system seeing as how they only came out in 93 and I'm tired of sticking the key in the door. I think the driver side tumbler is pretty worn.
What's neat is that if I use the power door lock in the car on my way out then the security system is engaged. If I use the remote to lock the doors then it isn't. Plus I get the hatchback to open with the remote too.
Graham
 

BigRed

Well-known member
Joined
May 23, 2001
Messages
948
Location
Edmonton
Corvette
1985 Bright Red Rocket
Problem is when you have an after market alarm that locks the locks when you run the ignition lol

I have an aftermarket alarm (ungo ms 2004) and a Avitar pager

Not to mention the operational stock alarm

I have problems with the new alarm locking the locks then me unlocking the lock via new keyless entry prob is the stock alarm doesnt reconize this and she goes off after I open the door


HALP :mad
 

Ken

Gone but not forgotten
Joined
Jan 30, 2001
Messages
8,236
Location
Hermosa Beach, CA
Corvette
1987 Z51 Silver Coupe
Hey Big, that's something you'll have to work out with your installer.

I have a Raptor system installed along with my factory system, although I have dis-abled the VATS for other reasons I won't get into here. My two systems both work as designed and in conjunction with each other.

Just don't let him screw around with the Corvette original system. :nono

Ken
 

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