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Ok guys serious problem with my Security System need help fast. (1990 Deville)

14K views 47 replies 8 participants last post by  Forgoten214 
#1 ·
Ok here is what is happening. Sometimes randomly I go to start my car and the security system will engage and will not let me start my car. I've tried everything from disconnecting the battery and certain wires under the hood on the vehicle. There is usually nothing I can do to fix this problem. After about 45 minutes the vehicle security light came off and allowed me to start the car. I'm not sure what its about but I noticed when I purchased the car it came with several ECUs in the trunk. Maybe the previous owner had similar issues. I'm not sure how to go about fixing this. I hope I can because I figure something like this I might have to go to a dealer for. I certainly hope not though.

Any help at all or if anyone else has experienced problems like this please let me know. This has happened to me 3 times now I'm pretty aggravated and fustrated with this problem. :rant2:

Thanks again in advance.
 
#4 ·
could this be a VATS problem? is the chip on the key worn down? the wires that come from the cylinder and go down (inside) the steering column to under the dash sometimes chafe as you turn the cylinder 1000's of times causing intermittent (or totall loss of) that circuit...

if they key's chip looks worn (flat, it should have a bump in the middle of the metal strip inside the black pellet) then try a new key first. it could just be your key is thinner now and can't contact always

if that doesn't work then maybe look into the wires ...

an alternate route is to disable/bypass the vats system altogether ... search bypass vats and you'll see some good posts (i had a few very long and informative posts in a couple of those threads this year)
 
#5 ·
Im not sure but my car came with 3 ECUs in the trunk so I assume the previous seller had the same problem. It's like playing Russian roulette with my car, never know if it will start or not.

I'm pretty sure its just a wire lose in the ignition or something. I hope someone here has some sort of solution. :worship:
 
#10 ·
what usually happens is that the contacts inside and the key's metal chip itself also get worn down and the distance between them gets further apart

at first it's okay but as they wear more and more the gap becomes wider and until it's too wide for the circuit to complete

if your key looks worn down a bit it's probably just the beginning stages and the gap's only going to get wider and this will happen more often
 
#11 ·
Ok but what are the chances of BOTH sets of keys being worn? It's unlikely I'd think. I have the Gold and the Black master key. When the security problem happens both keys are interoperable. So that's why I don't think its the key but a problem in the ignition itself.
 
#14 ·
the new cylinder will come with a new code (the cuts on the key) and a blank key with no chip ready to trace onto a key with a chip that has the same value of your current key

the problem with doing this is that now your keycode is no longer the same keycode that all the dealers have on file so you can't go to them for help if you lose all your keys (or the future owner, etc)

so the solution to that is that when you buy a new cylinder take it to a locksmith and have them re-code the tumblers in the cylinder to match your current key so you don't end up changing the keycode
 
#16 ·
I have the same car with the same problem. Took it to an electric shop. They say the security wire on the cylinder got pinch by steering gear in column causing it to contact at times but not all the time. Switch, Locksmith, and Labor cost me $350 and guess what.....still didn't fix it. Car immediately went back to its old self within days. My theory is that this car just has a flaw in itself where as the steering column and the way the wires are run conflicts with each other. Im probably just gonna bypass the factory security as stated above. Seems like the best, and only bet.
 
#21 ·
Yep I did, they want me to break the steering column and add a resistor to the ignition line. :bonkers:

They must be insane, I thought there would be an easier way to do this. I'm not so sure I want to cut and solder in some resistors. Seems pertty fishy to me. :bonkers:
 
#23 ·
you can tap into that circuit in easier places... find those wires as they leave the steering column base and go under the dash...
http://www.google.com/#q=bypass+vats+site:cadillacforums.com
I don't know man, I'm terrible when it comes to electrical stuff. I bought the resistors and the key tester thing but I just couldn't figure it out. I returned it back to Lowe's. Is there anyone locally that might know how to do it and not charge a insane amount of money to do it? :bigroll:
 
#25 ·
Yea I set the electrical crap to 20k and i was getting a reading on the key of 150. So I tried matching the resistors I think I found a 150 resistor but now where do I put it in? I probably sound like an idiot which I am but this crap is really a PITA.
 
#26 · (Edited)
think of it this way:

you're doing a bypass... you're bypassing the chip in your key...

the chip in your key completes the circuit when you stick it in the cylinder

so you cut the two wires and disregard the sections that go up the column to the cylinder and put your resistors in between the other two wires that go back up into the dash up to the module or cluster
remember to put the resistors in series if there's more than one, not parallel (tie them together end to end, not all together)
i don't recommend you cut the wires though... so keep reading

the two wires come from the ignition cylinder down the column into a connector block in the the lower dash just above the pedals
the connector block has other things plugged into it, but basically it collects these different wires from the dash and on the back side of the connector is one part of the big dash harness that connects just about everything in the dash

you can just unplug the connector for the cylinder wires at that connector and plug your resistors into the two terminals

if i was doing this job for myself i would do it something like this:
get my resistors in order ... test them against the chip in my chipped ignition key (there is a tolerance they don't have to be exactly the same)
then i would unplug that connector under the dash for the wires in question and plug in my resistors into the terminals vacated by the connector i just removed
next you try to start the car and see if your bypass worked...

once you've verified that your temporary bypass has worked you can then start making it a more permanent solution
there's various ways of doing that... one is to cut the wires off the connector that you removed leaving only an inch or so of wire after the connector and adding your resistors in there
some people go behind the junction block and wire in there...
some people go further up into the dash or behind the IPC ...

once that's all finished go get an ignition key cut without a chip in it for use as a backup key
(B-62 blank at your nearest dealer or locksmith ... we charge only $2-$5 for those types of keys)
 
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