GM Passlock Security Light Issues

In this article we will be looking at various factory-installed General Motors anti-theft systems. Outlined below are some of the common problems and solutions to those problems. Also included are the functional characteristics of each system, commonly referred to as VATS, Passkey, Passlock I, Passlock II, Passlock III (PK3), and Immobilizer.

Symptoms and Solutions


  • Passlock system fault code B2960
  • Security light flashing
  • Engine starts and dies

If you find yourself stranded, your engine won't start, and the security light is flashing, wait ten minutes. The flashing light should go off or illuminate without flashing. When it does, turn the ignition off, wait twenty seconds, and then try to start the engine. If it starts and runs, you should be able to make it home. Please remember that this is only a temporary fix; the fault will happen again.

The most common repair is to replace the ignition lock cylinder or Passlock sensor and perform a relearn procedure.


  • VATS (Vehicle Anti-Theft System)
  • Security light on steady
  • Engine won't crank—all other systems functioning normally

If you find yourself stranded and the engine won't crank over, turn the ignition off and wait four minutes. Then, try again. If the engine starts, you should be able to make it home. Please remember that this is only a temporary fix; the fault will happen again.

The most common repair is to replace the ignition lock cylinder due to broken wires inside the steering column.

Get it diagnosed by a professional


  • The Passlock I system was introduced in mid 1990s
  • Passlock II and Passlock III (PK3) systems were introduced shortly after
  • VATS system were introduced in mid 1980s

Anti-Theft Systems

Depending on the make and model, there are various factory and aftermarket anti-theft systems. In this article, we are concentrating on factory-installed GM starter interrupt systems. This type of anti-theft system is designed to prevent the vehicle from starting unless the correct ignition key is used.

These systems used a dash-mounted "security" or "theft" light which can be yellow or red in color. Depending on the current status of the system, the warning light will be off, on steady, or flashing.

Although they may share the same dash-mounted warning light, these "starter interrupt" anti-theft systems work separately from and independently of the "content theft" systems available from factory and aftermarket suppliers. Content theft referrers to anti-theft systems that sound an alarm when a vehicle is broken into.

Two Types of Systems


In the mid 1990s, the first Passlock systems were introduced and are still used to this day. The Passlock I and Passlock II systems use a sensor in the ignition lock cylinder, which looks for proper rotation of the lock cylinder with the correct key. Upon successful rotation of the ignition lock cylinder, a code will be sent to the Passlock module.

The Passlock III system uses a transponder located under the plastic covering of the key. In most cases, these keys are stamped "PK3" on the metal blade near the plastic covering. An antenna located at the entry point of the ignition lock cylinder reads the transponder data from the key and sends a code to the Passlock control module. This system is very similar to the immobilizer system used by many other manufactures.

The Passlock III antenna and the Passlock I and Passlock II sensors in the lock cylinder are all commonly referred to as Passlock sensors. Upon receipt of the code from the sensor, the Passlock module will match the code received to previously learned values. If there is a match, the Passlock module will send a signal to the engine control module to allow the engine to start and run. The Passlock module is commonly part of the Body Control Module (BCM) or Instrument Panel Cluster (IPC).


In the mid 1980s, we first began to see the "VATS" (Vehicle Anti-Theft System). It is easily identifiable by the "resistor" mounted in the metal blade of the ignition key. There are fifteen different resistor values available. In order for the engine to start, the correct "resistor" must be read by the VATS control module via the ignition lock cylinder. Also, the ignition lock cylinder must be rotated to the "crank" position. If the incorrect code is read, the system will not allow the engine to start for four minutes—even if the correct code is received. The security light will remain on or a message will be displayed on the Driver Information Center (depending on the model) when this occurs.

Both of these starter interrupt systems are very effective on their own. If you install an aftermarket alarm system, be advised that the starter interrupt feature can cause problems with the factory-installed systems. If you are considering installing an aftermarket alarm system on a vehicle equipped with a factory-installed starter interrupt, you should consider not installing the interrupt option. 

What Does the Warning Light Mean?

Security LightSecurity Light

Operating states of the warning light on Passlock systems should be:

  • On for bulb check
  • Off when engine is running
  • On steady if a fault occurs
  • Flashing in the learn mode

Under normal operation, you should see the warning light on during bulb check and off when the engine is running—no message displayed on the DIC.

When the system detects a fault, the warning light will illuminate or a message will be displayed on the DIC, depending on the model. If a fault occurs while driving, the engine may or may not start after turning the ignition off. If a fault occurs when trying to start the vehicle, it probably won't start.

The warning light on the VATS system is similar except it does not have the learn mode.

Common Problems

Most common problems related the the Passlock family involve the Passlock sensor. The sensor is part of the ignition lock cylinder on Passlock I and Passlock II systems. The antenna is the Passlock sensor on Passlock III systems. If these sensors fail, the proper repair would be to replace the failed part and perform a theft system relearn procedure.

You may find information elsewhere encouraging you to bypass the Passlock system. You should try this at your own risk. If you decide to bypass your Passlock system, please contact us with the outcome so that we can pass the information along.

By far, the most common problem with the VATS system is broken wires in the steering column. These wires connect the ignition lock cylinder to the under-dash wire harness. The proper repair is to replace the ignition lock cylinder, which comes with wires already attached that snake down the steering column. The new lock cylinder will come with a key blank that will only rotate the new lock cylinder—it does not have a resistor in it that will allow the engine to start and run. A new key must be made from the blank because it has the proper resistor value. Normally, the resistor is read from the old key using a tool called an "interrogator." The interrogator is available in the parts department of most GM dealers.

Relearn Procedures

The Passlock family has two basic relearn procedures—a ten-minute procedure and a thirty-minute procedure—and which one you use depends on the system and what components have been replaced.

The ten-minute procedure involves trying to start the engine. If nothing happens or the engine starts and dies, the security light will be flashing. Wait ten minutes. The flashing light should go off or illuminate without flashing. When it does, turn the ignition off, wait twenty seconds, and then try to start the engine. If it starts and runs, everything is okay. If you get the same result as previously—nothing happens or the engine starts and dies with the security light flashing—wait ten more minutes.

You will now begin the thirty-minute relearn procedure, which is just the ten-minute procedure repeated three times. After turning the ignition off for the third time and waiting for twenty seconds, the engine should start and run. If it doesn't, there may still be something wrong with the system.

After the learn procedure is completed and the engine is running, the security light may stay on steady for a few minutes and then go off—this is normal. Depending on the system, replacement of key components will necessitate that a relearn procedure be completed. These include the ignition lock cylinder, Powertrain Control Module (PCM), Body Control Module (BCM), or Instrument Panel Cluster (IPC).

Unless the VATS control module is replaced, there is no relearn procedure for the VATS system. A new VATS module will learn the resistor code the first time it is powered up. Once the module learns its code, there is no way to relearn it. New ignition keys must always be matched to the learned code in the VATS control module. If all keys are lost and the VATS code is unknown, then use trial and error to find the correct VATS code. (In some cases, the VATS code may be available from your local General Motors parts department.) If the incorrect VATS code is read by the control module, the system will not allow the engine to start for four minutes—even if the correct code is received.

17 User Comments

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By , May 10, 2010
I did exactly what you said, and wow, it worked,, thank you so much
By , June 25, 2010
Just an FYI (since there are literally thousands of posts online regarding this problem without GM 'acknowledging' it.)
By , June 25, 2010
Facebook Group for recalling the Passlock systems:!/group.php?gid=129805317054124&ref=ts NHTSA website (to report your case to the national highway safety transportation administration.) Just imagine if your car were to stall in a dangerous area and this Passlock system wouldn't let you start your car. I don't mean to be dramatic, but what if this was on railroad tracks with children in the backseat? Not a safety issue? Please GM, get real.
By , August 13, 2010
Here is the best solution to bybass this junk security system that GM put in their cars. Mind you, once installed, you don't have a security system anymore, but it will save you the headaches and runaround with the high cost "stealer" shops. Check it out at:
By , December 18, 2010
Thank you for this information. My wife was stranded with her Saturn Vue only able to start for two seconds before stalling. I was able to use the 30 minute relearn procedure successfully. You save me a towing bill and a trip to an auto repair shop. THANK YOU!!!
By , December 21, 2010
Check this out... I own a 1999 K3500 Chev pickup and I was certain the passlock disabled the vehicle.Fuel injectors did not work and the security light dash on. Every thing else on the truck worked.I worked on the problem about an hour to outsmart the passlock.What I found was the battery terminals required cleaning and the negative wire from the battery post to the fender needed a new terminal, cleaned screw hole in fender to shiny bare metal, and fastened with new screw. Result: Vehicle started on first crank,test drove a half tank of fuel arount town. Service completed.
By , December 27, 2010
Its really sad that GM is blaming it on the driver insted of fixing the problem that so many people are having.
By , February 02, 2011
It’s when the security light starts flashing that the infamous “chip” in the key becomes a nightmare to many. Gradually the car begins not cranking anymore or if it cranks it would start and die in a second. Randomly it will do this more and more often until it won’t start anymore. VATS, PASSkey and Passlock immobilizer systems are killing cars all over North America, they have a short lifespan and are certainly more effective against owners than thieves. Here is how you save your car 1st 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 regal for more than a year. If its shuting down while running, im sorry i have no quick fix... Cheap fix: Bypass the chip in your key. Temporary, but effective. Until the TDM (theft deterrent module) in the dash poops out, then you're kinda screwed. I was told that these types of key security systems have a 7-10 year life span. Sucks for us. This link explains the "Key Issue" pretty well. ----- Never worry again fix: Bypass the whole VATS/Passlock/passkey I or passkey II system entirely. Literally take it out, and throw it away. I just did this in my Regal. Took about an hour. Took longer to find the thing than it did to fix the problem. For a list of cars effected by this problem. See the NEWROCKIES link on the right side of their page......... They sell a unit for 200 bucks to totally bypass this system FOREVER. life time-money back and all that. Finally did this in my car. Well worth the 200 if you've looked into getting this replaced... Anywhere from 600-1000 bucks. ----- ----- With this fix, you can take that whole Vats, passlock, passkey **** system out of your car all together. Good info on both sites It works for: Any GM or Isuzu Vehicle with VATS or PASSKey or PASSLock security systems. If your car has the chip in the key or in the lock cylinder, then you can save it with this Full Bypass. Trucks . GMC/Chevy 1998-2006 S10/T10/Sonoma /Blazer/Jimmy 1998-2007 Suburban/Avalanche /Tahoe/Yukon 1998-2006 Sierra/Silverado 2002-2008 Trailblazer 2003-2006 SSR 1998-2006 C1500/C2500/C3500 1998-2006 K1500/K2500/K3500 2003-2007 Hummer H2 . Isuzu 1998-2000 Hombre 2005-2006 I280/I350 2007-2008 I290/I370 . Cars/Vans . Isuzu 2003-2007 Ascender . Pontiac 1994-2003 Grand Prix 1998-1999 Montana 2006 Torrent 1996-2005 Grand AM 1994-1998 Trans Sports 1988-1999 Bonneville 1988-2002 Firebird 1995-2005 Sunfire 1996-2002 Trans Am . Buick 2004-2007 Rainier 1994-2005 Century 1993-2004 Regal 1982-1999 LeSabre 1991-1996 Park Avenue / Ultra 1994-1996 Roadmaster 1991-1996 Roadmaster Estate Wagon 1982-1999 Riviera 1988-1991 Reatta 1996-1998 Skylark 1982-1990 Electra (all models) . Oldsmobile 1996-1998 Achieva 1999-2004 Alero 1994-2004 Aurora 1998-2004 Bravada 1991-1993 Delta 88 1994-1999 Eighty-Eight 1991-1996 Nighty-Eight 1998-2002 Intrigue 1990-1992 Toronado 1994-1997 Cutlass Supreme 1997-1999 Cutlass 1997-1999 LSS/Regency 1997-1999 Silhouette 1991-1996 Custom Cruiser . Chevrolet/GMC 1998-2005 Astro/Safari 1998-2008 Envoy 2005-2006 Equinox 1998-2007 Savana/Express 1995-2005 Monte Carlo 1997-1999 Venture 1995-2001 Lumina 1988-2002 Camaro 1995-2005 Cavalier 1982-2004 Corvette 1994-1996 Caprice/Caprice Wagon 1995-1996 Impala SS 2000-2005 Impala 1997-2005 Malibu Classic 1997-2003 Malibu . Cadillac 1986-1993 Allante 1982-1996 Fleetwood 1985-1996 Fleetwood Brougham 1992-2004 Seville 1992-2004 SLS/STS 1985-1999 Deville 1994-1999 Deville Concours 1997-1999 Deville D'Elegance 1988-2002 ElDorado 1994-2002 ElDorado Touring 1999-2007 Escalade . Saturn 2000 LS/LS1/LS2/LW1/LW2 2001-2002 L100/LW100 2001-2003 L200/LW200 2001-2005 L300/LW300 2004-2005 L-Series 2002-2008 VUE 1996-2002 SL/SL1/SL2 1996-2002 SC1/SC2 1996-2002 SW1/SW2
By , April 21, 2011
Thank you Thank you Very Much! we have a 2003 Saturn Vue that had the key tumbler go bad & would not turn at all - I replaced the whole key tumbler housing. Wouldn't start. Did the 10 minute - 30 minute thing many times - didn't work. Waited 40 minutes & tried again. This time I did the 10 minute thing until the flashing security light went off, turned it off for 5 seconds - no start. Did this two more times & IT WORKED YEAH! By the way, the new key mechanism housing no longer have a steering wheel lock - Saturn had so many problems with them they removed them.
By , July 08, 2011
General Motors has been served with a class-action suit. The litigation originates from owners of 2007 and 2008 Impalas. The suit alleges that faulty rear spindle rods are causing tires to wear too easily. In 2008 GM resolved the problem for Impalas sold as police automobiles, but not to customer motorists. General Motors could hand out millions if the suit succeeds.Here is the proof: <a title="General Motors faces class action lawsuit over abnormal tire wear" href="">GM faces class action lawsuits over excessive tire wear</a>
By , July 17, 2011
I am the original owner of a 1998 Pontiac Sunfire. Just turned 100,000 miles a couple weeks ago. Have maintained it with TLC. Looks new, ran perfect until two weeks ago. Drove to store, came home. After five minutes went to start it in the driveway and nothing, no click, no nothing. Replaced starter switch, nothing. Checked continuity on all wires, all good. Voltage at starter 12.5 VDC. Clutch safety switch checks OK. Replaced ignition lock cylinder from dealer ordered for my VIN number and set to use my original spare key with no wear. Performed the 30 minute relearn procedure, nothing. Replaced the battery, and performed the relearn procedure over 9 more times. Then I learned I need to leave the ignition switch on for one hour to clear all discrepancies and then perform the 30 minute relearn procedure. Nothing. Did the one hour + 30 minute relearn procedure again, nothing. I've been working on this car for five days and spent nearly $400. There are no words to describe how angry I am and to say I won't ever buy another GM product again is only part of my sentiments. Tomorrow I'm having this car towed to the local GM dealer and they will probably charge me an incredible amount of money to hopefully fix this car so I can trade it in on a Ford or Chrysler product.
By , June 14, 2017
I have the problem where the Security light will sometimes come on while driving, and will sometimes come on while I am starting my car. This often means that I can turn my key afterward, but it will not start. I have found ways to get around it, but this usually requires a process of waiting 20-30 minutes before the car will finally start. I have no idea how many times I have been late to work, or have been stuck in a less than ideal place for an extended period of time thanks to this issue. This all started after the cobalt ignition switch recall, when the dealership REPLACED the ignition switch AND the key, and now it is like my key is not recognized at all. I tried reporting it to GM, but of course they came back asking for information about what dealership I took it to, and what the dealership said. I do not have time to take it to a dealership, just for them to not be able to figure out what the problem is, especially since it is not a problem that I can get to repeat on command. Or they will do something saying they "fixed" it, charge me a whole lot of money (as dealerships do), and it will not actually fix the problem. Then I am out the time AND money, and I still have a car that periodically turns into a very heavy, expensive paperweight. GM (as per usual) refuses to acknowledge that there is a problem, because that will cost them money to fix. And since it isn't TECHNICALLY a safety issue, they see no legal obligation for a recall. I highly doubt I will ever buy a GM product again.
By , June 27, 2017
I have a 2005 Cavalier. we installed an aftermarket stereo with the proper clips and now my alarm system has gone insane! I pulled the stereo out and my alarm is still insane. after I got past it killing my car so I had to be towed (with the 30-minute relearn), I still can't shut the alarm off. up until two weeks ago I never even knew it had an alarm.anyone have any ideas on how to shut this thing off? I mean honestly, no one would want to steal this car!
By , September 09, 2017
worked !!!!!!! no security light starts right up thanks alot ....... 30min reset > :)
By , May 28, 2018
Did you spray any graphite, WD 40 or lubricating oil into the lock cylinder ??? Now you need to spray that out of the cylinder because it will cause the security light to come on when you try to start the car. Especially in summer when it is over 100 degrees outside. It will start in the morning going to work but coming home it will flash 3 times and the car will not start. Then after 3 or 4 tries the car will start when it is hot outside. Then one day the security light will stay on and flash for 10 minutes. I sprayed a lot of throttle body cleaner into the cylinder to clean out the graphite, WD 40 and lubricating oil that I sprayed blindly into my cylinder over the years. I cleaned it 3 times over a 6 hour period. Warning - Don’t start the car! Wait at least 24 hours for it to dry – Throttle body cleaner Flammable!!! Then first start the car in the morning – Then again in the afternoon when the car is nice and hot in the sun. Don’t go anywhere – Maybe drive 10 miles and then come home in the afternoon and wait 3 minutes to see if the car will start in the heat - 100 degrees. Then don’t spray a thing into the cylinder again – I recommend that you let a locksmith change the cylinder key pins and tumblers – There is a kit online – Plus it has match your old key exactly or else the car will not start. Security Light! In the future don’t spray any graphite, WD 40 or lubricating oil ever again into the key ignition lock cylinder. I had this problem with this every summer for the last 2 years and it will start getting worse and worse until you clean the cylinder. The Pass Lock system in Saturn’s measures the pin length on your key in the ignition and it has to match exactly – It doesn’t use a chip in the key - Good Luck !
By , July 07, 2018
Over the past few years I've learned the hard way dealing with the pass lock system. The first thing I did was call the local Chevy dealer for an estimate of repair. After hearing $750 I sat down because I thought I was having a heart attack....... Then went directly online and of the bypass kit but settled on the resistor method. The method worked for several years and then it started acting up again. I did everything I thought I could do but still had the problem. It was very inconsistent and I couldn't tell if I fixed it or not. Finally spoke to a sharp GM mechanic. Suggested I checked over every ground wire I could. Battery to body wall, to engine, engine to frame. Found a hidden corroded battery to engine ground wire. Pulled on it and it was only connected by a couple of strands. I resolved the issue but while talking to everyone I could think of a local guy turns me onto the local locksmith. $110 later I'm back to normal. Wired it back up without the resistor drove her over to the locksmith. New barrel new key (GM) and no more trouble. Just wanted to state that a local locksmith may be able to serve you right for around $100 rather than got through buying a bypass kit of dealing with any of the methods.
By , October 28, 2018
I have written to them I have called them they have done nothing and will not do anything. I ws told to take the car to one of their authorize dealers Felix Chevrolet. In Los Angeles near USC. They charge $160.00 to look at it and will add the 160.00 to the work that has to be done. Even though my car has 112417 miles now its a 1999 Pontiac Grand AM SE. GM want do anything about the security light it has to come out your pocket. Why did they put that system in. You could get kill because you can't get away. You are stuck like a duck in the mud. after waiting 14min for your car to start.

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