Question about 1991 Cadillac DeVille

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1991 sedan deville security system car starts at times then at times security stayes on ireplaced key and wire what else could cause problem? could it be in ignition switch itself?

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The security system (VATS/Passkey) installed on these GM cars is anti-owner more than an anti-theft. There are 3 parts involved:

  1. The chip-key
  2. The lock cylinder
  3. The TDM (aka the brain of the system)
if any of these parts fails or is even slightly malfunctioning, the car stays stuck where you are and you only get a dealer asking you about 1,000$ to fix it. And all the 3 parts have a quite short lifespan. Way too many people got in this situation (including myself). I don't recommend any partial solution or any used parts as it would happen again way too soon to be acceptable and if it happens 100 miles from home (like it happened to me....) it's a big burden. I finally made it to save my beloved 94 Park Avenue (with the exact same system that is installed in your car) with a solution that I found on the internet and that bypasses the entire factory security system, all 3 pieces altogether and you can even remove the TDM at the end and use 99c keys without chip. The product I used is at and is still working perfectly after 5 years. Don't go to the dealer!

Posted on Feb 28, 2011


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I was hooking a new stereo up in my 1991 Cadillac sedan deville and sparked a wire and now its running rough. what could it have did?

What you did was sent 12Volt Power through the Entire car. There is no way for ANYONE to know what damage you have caused. The Computer could be fried, Sensors, the list goes on and on as you can tell about putting the Old Stereo in and it working..

This is the same as Jumping your car and putting the wires on backwards... Only Worse, you bypassed the Security Features of the Fuses....

Sorry but you are going to have to troubleshoot every system to find out what damage has been done

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Anit theft prevents car from starting

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How to disable security on 1993 cadillac sedan deville

find the orange covered 2 small white wires as they exit underdash from the steering column. cut the 2 wires and solder in a resistor on the wiring side of the vehicle[not the column side. use an ohmeter on the key itself to find the ohm value in the range of 725-1200 ohms. get a resistor of within 50 oms of the key,solder in as described,drive off.

Jan 14, 2011 | 1991 Cadillac Seville

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Need to bybass security system to start car on 1992 cadillac sedan deville

Hello: To by-pass the security system you need to do the following; Take your key to radio shack have a knowledgeable sales person read the Resistance value of the resistor in your key(ignition) and sell you a resistor of that value. Under the drivers side dash there is a large electrical connector near the park brake assembly with two smaller connectors on each side. One of the smaller has two small white wires on one end. (these are the wires that come from the lock cylinder of the key cylinder) Wire the resistor in to these wires going to the connector (front of the car) NOT TO THE WIRES GOING TO THE STEERING COLUMN. This will allow the car to start asnd run but you will NOT have the protection of the anti theft of the system.

Nov 11, 2010 | 1992 Cadillac DeVille

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I have a 1991 Sedan deVille. If I try to start it with the key, it does nothing. All the accessories work with the key in the run position. If I bypas the ignition system, it starts just fine. What could...

So you have no crank no start correct. Three possible items to check : ignition switch,neutral safety switch, starter relay. and if applicable starter interrupt relay.

Aug 23, 2010 | 1991 Cadillac DeVille

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I have a 91 Cadillac Deville that will not start. It does not crank or even try to start. A while ago, I ran the battery down, and then was able to jump it and it ran fine. Then, I left the lights on...

Try turning the key to the on position and wait for the security light to stop flashing (usually ten or fifteen minutes) then turn the key off and try to start it. On some you need to do that procedure three times without starting but most will re-start after doing it once. Usually this will work to re-set security on GM vehicles.

Sep 21, 2009 | 1991 Cadillac DeVille

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Bypass security system on a 1988 Sedan seville

If you have the chip in the key, this is the method I used for bypassing the entire security system and never heard about it anymore:

Jan 27, 2009 | 1988 Cadillac Sedan DeVille

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1991 cadillac sedan deville

get new key with newer chip or replace ignition cylinder.

Sep 22, 2008 | 1991 Cadillac DeVille

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