Welcome to my site. This site is completely informative. It is to help educate and guide in the diagnosing and trouble shooting of security light, "no start", and engine immobilizer problems on GM vehicles using Vats, Passlock, or Passkey antitheft security systems. If you see a light that says SECURITY, ANTI THEFT or the picture of the car and padlock on your dash when your car won't start, you HAVE an anti theft issue. These icons are for the antitheft system only. They are not tied to anything else. DO IT YOURSELF fixes near middle of page for most vehicles. 

Yes, the above key is a Ford key, but i couldnt find a picture of a GM with the transponder showing. But you get the idea 


                          ^ THIS IS A TDM ^



This is a  BCM (Body Control Module) This one is out of a Grand Am, but will look very similar to this in these vehicles.

1999 - 2004 Oldsmobile Alero
1997 - 2003 Chevrolet Malibu
1999 - 2004 Pontiac Grand Am



Vehicle owners causing security issues.

Sometimes we cause these issues ourselves. If you have done any of these things, this may be the reason that the security is messing up.

1) Excessive keys and keyrings hanging from ignition

2) Motor swap. Changing out you motor with a new one or different one, confusing the security system and causing a break in the SECURITY communication.

3) If you have replaced the ignition. This is a very important part, it must be replaced by original GM parts and NOT cheap Auto Zone parts. It then must be reprogrammed by the dealer or you for your system to work.

4) Low batteries can cause this. The system reads low voltage as a security threat.

5) I've also heard this a few times. "My dash lights went out, everything else works, but my car will not start and the security light is on." Maybe part of the security system is powered by the dash..... Just a note, ive seen this issue about 4 or 5 times

6) Remote starts cause all sorts of problems on GM security systems. It is best to NOT ever install one, or if you start having problems, remove it before trying anything else. In order for a remote start to work, the installer must tamper with this antitheft system, or else the vehicle wouldnt start at all. Needs the key chip or transponder.



After performing either of the following bypass procedures, your vehicle's factory starter or injector interrupter will be disabled.  A thief will be able to steal your car much easier than if the security system was still enabled. It DOES NOT eliminate having to use the key, it just makes your car and key work like a regular car and key. No anti-theft or security will be present. The thief would STILL have to hotwire the ignition to steal it, just like any other car.

I hope that this site was helpful and informative. I've put alot of time and effort into this page and will continue to do so. If you find a good picture that will help on the site, or find any other ways to bypass or fix these systems, leave me an E-mail. And when i know it works, i'll post it to the site. If you have any comments or questions, feel free to ask or let me know. E-mail located in the "Contact Us" tab.


Also, feel free to use this link however you want. If you find somebody somewhere in the same situation, and this site will help them. Hook em up.  Don't take this to a Dealer mechanic. Lets stop GM from stealing our money when they know this system is failing. Think about it, The system has been failing since 1982. Thats 30 years. Look to the right, there are year 2010 vehicles in that list, and probably more to come. You think they would figure this out, the only thing they figured out, is how to get more money from us, ON TOP of what we paid for the car. Not to mention getting money from the 2nd or 3rd owners too.  SHAMEFUL!   Hope this site helps you.



                   (Next car's gunna be a Ford)

Well after realizing that ford and just about EVERYBODY else has failing antitheft systems, i got an Oldsmobile. When it breaks, at least i'll know how to fix it.







The security light is a visual indication that something in the car's antitheft system is failing.  In most GM cars and trucks there is a hidden system that most people are unaware even exists. From the moment you put your key in the ignition, there begins a constant line of communication between your key's security chip or transponder, to the ignition's lock cylinder, and then to the car's TDM (Theft Deterrent Module). These 3 parts are in CONSTANT communication. If the key is in the ignition, then these parts are sending signals to each other. The security light illuminates when that signal gets broken, even just for a second. When the signal breaks, the car misinterperates this as an attempt at theft and goes into antitheft mode. The car thinks its being stolen or hotwired because it is not getting that signal from YOUR specific key. This is why the security light turns on and shuts down your vehicle. Remember too, the TDM controls the security light. Sometimes you can have ALL the symptoms and no lights.

I have put this site together to help others out with this problem. Ive added things at different times so im sorry if the info is choppy or if there are things described twice. By no means am i a professional, i have just collected alot of info and put it on this page to help as many people as i can.




Normally on older cars there is a black resister chip in key which "communicates" to the lock cylinder. Sometimes it is hidden in the plastic part of keys in new models. Same concept, might say PK3 or might have a "+" sign, a + with a circle around it, ive also seen 2 dots on some Saturns. . . The newer ones work on frequency and transponders. Same concept. The key sends a signal that is read by the ignition.

Inside the ignition lock cylinder there are pins that read the chip in the key OR the part that reads the frequency on newer models. So the key sends the signal, the ignition reads it and sends that info to the TDM.

3.The TDM
Theft Deterrant Module-Sometimes called the "computer" or "brain". This is the part that sends the signal (**NOTE**) to your car's starter or injectors and allows your car to start or continue running depending on your type of system.

If any of these parts are not communicating properly, your SECURITY light will come on and shut down your vehicle. The idea being, that without the chipped key or frequency key communicating with the ignition and then to your TDM and then to your starter or injectors, the vehicle wont start and can't be "hotwired" or stolen. Pretty nice when working, but these systems are flawed and the average life is 6-10 years. Tampering around with these parts can also cause problems. So many times i've heard of people changing the ignition, starter. or fuel pump and setting off the security system. I've also seen people try to change out these parts to try and fix the security. The concept being, if the key, ignition, and TDM don't match. The security will fail and shut you down. I've also noticed that weather can effect these things. Hot or cold days used to set my anti theft off ALL the time. Every single aspect of this system is expensive to replace and can only be worked on by "authorized" GM service men without voiding warrenty. Most garages dont even touch them and if they do, they will sell you every part they can before "fixing" the problem. If you have looked into replacement or fixing these systems, you should know that the cost is very high and may actually be more than the Blue Book value of your vehicle. Lets face it, alot of us drive beaters.

  1. The Key and Lock Cylinder component ($350).
  2. The Theft Deterrent Module (TDM) or Body Control Module (BCM)
  3. (aka the Brain of the system – $700)
  4. The wiring between #1 and #2
  5. Plus anything else the dealer can and WILL try to sell you. Starters, batteries, injectors, fuel pumps, selenoids, keys, ignitions, LABOR, ect ect........................


Symptoms of a Security system failure. This is for any GM vehicle with a Passlock,PASSkey,and Vats antitheft security systems.

1) A light saying SECURITY or ANTITHEFT is illuminated solid or flashing

2) A light shaped like a car with a "padlock" through it is on or flashing.

3) The vehicle will not start. The starter will not even click and everything else in the car will work fine. Security light will be on.

4) The engine will start for 1-5 seconds and then stall, followed by a security light .


I had crashed my good car into a snowplow so i bought a car from an "acquaintance" very cheap. 1000 bucks for a 96 Regal with a ton of miles but should get me through the winter. First i started to notice intermittent starts. It would act up one day, then be fine for weeks. Run great for a few months, then would not start when i needed my car the most. This only got worse and more often. I thought i could just keep doing that 10 minute key trick (described below) forever, but NO. (i did do it for the better part of a year though) The final straw for me was when i had my daughter in the car ( 5 years old at the time ) leaving a Walmart, it was a below freezing Illinois winter and the thing would not start. Having to tell her that we have to run in the cold and ice to go back inside and wait ten minutes for my car to start was heart breaking and embarrassing. She did not understand. I then decided to get this fixed. Every place i took my car to was talking about 600-900 bucks for a TDM replacement. I knew there had to be a cheaper way. And of course there IS.



1st trick
Try a spare key that is newer or used less. The pins wear down with use and so do the keys causing the security to fail. Transponders can get damages or lose power and fail as well/

2nd trick (10 minute trick)
(if not starting) Turn the key forward 2 clicks till right before it would normally start, leave like that for 10 minutes. ( no less ) After 10 minutes, turn key back then forward and your car might start. I did this in my Buick for more than a year. If its shutting down while running, I'm sorry I have no quick fix...

Note that if you can see the little black chip in your key shaft, then you have a Vats system. If the ten minute trick works on this system, then the problem is NOT in your key or ignition. It is the TDM itself. It will have to be fully bypassed or a new TDM installed. This system does not relearn or reteach the ignition like the passlock and passkey systems do that came after them..


 (Only ignition and key bypassed)

I used to have a link to a webpage here, but the owner of the page requested that i remove his link. So i will give you a basic rundown from my knowledge. 

On the VATS system's ignition cylinder is an orange wire coming off the housing. Inside the Orange shielding are two white wires. These wires are what read the OHMS of the chip in your key. So basically you can take an OHM meter and read the OHMS between the sides of the chip in your key. Whatever the reading is (one of the 15 listed below) you can reproduce this with simple resisters from Radio Shack or some place like that. You place your resister pack between these 2 white wires, and you've now bypassed the ignition and key. This is an inexpensive way to do this, and it can work well, but i strongly recommend only using it for a short time. I did this in my Regal and got stranded not long after with a hefty tow bill. The system isn't designed to read that constant signal and you will kill your Theft Deterrent Module even faster.



(everything bypassed. Ignition, key and TDM)


Well since the lifespan of these systems are so short, and are extremely expensive to fix, my only perminant suggestion is to eliminate it completely. After a year of doing the 10 minute "Quick Fix" and a "key bypass" that lasted 2 months and stranded me, i have only one good suggestion. After surfing the web for hours through forums and websites and paying for parts that i didn't need, i found this link - http://newrockies.com/passkey


Save this link to your favorites. --------^ You will probably end up needing it sooner or later. On the left side of the screen under the picture, there is a link that says "PRO VATS full bypass", this is where you will find the part you need. They sell a Pro Bypass Module that eliminates the chip, the lock cylinder and the TDM. Thats EVERY part of the system. It replicates the signal (**NOTE**) from the TDM and sends it directly to the computer and then to the starter or injectors and so on. Thus eliminating the ENTIRE system COMPLETELY. I came upon a fork in my road. A TDM that costs $700 for my $1000 car, or spend the $190 for this bypass, or just throw my car away. Lets say i now drive a Buick with the chip ripped out of the key and the TDM sitting in my glovebox for "show and tell". No problems since. I just told myself "I'm not spending 200 bucks, im saving a 1000".

Here is a list of known effected cars that can be fixed with the Newrockies bypass. This is the same list from their site and may update. Double check the list on the site. If you dont think you can install this part on your own, remember you can always ask your mechanic to help. When i did this on my buick, it took me about 30 minutes to find the TDM (thats without knowing what it looked like, you now have a picture) and about 10 minutes to install the part. I am not a mechanic. Just an average handy guy.



For the record, i made this site in MAY 2011, looks like i just rolled over 110,000 hits.... How common of a problem would you say this is???


15 possible OHMs readings for Vats keys and ignitions. 

                                   "KEY BYPASS"             

Codes in Ohms decimal 

  1———— 0.402
  2———— 0.523
  3———— 0.681

See minimum and maximum Ohms in below graph

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