GM's Theft Code B2960 | Key Code Incorrect but Valid

General Motor’s Theft No Crank/No Start Security Relearn

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GM Key Lock Cylinder and Passlock Sensor

I am sure many of you have had a GM towed in as a no start and when you go out to try to start it, it fires right up. Well we know many things will do this like the fuel pump, ignition components, starter, etc. So you then go and scan the vehicle and you get the code B2960 (key code incorrect but valid). I also get a U1000 code a lot with this code which may be related, may not be. The information I give from here is from what I have seen and is my opinion for some of the problems that cause this code.

When I get the code B2960, I will look through the security data pids for any problem. I will see if there are any other codes in any of the other modules. I will check the key code voltage and see if it matches what it wants to see. What I do next if there are no other codes that I think relate to the no start, the key code voltage is correct, no other security data pid problems, and after clearing the code it does not reset and the vehicle starts. First thing I will do is test the battery electronically with my midtronics tester and then load test it. Next I will check power and ground connections. My next step is the most important once you get this far. I will call the customer and ask them a few important questions; when did you see the security light and do you turn the key to on before you start your vehicle. If the customer says the security light came on while driving and the no start happened later, then my diagnoses will go a different direction. If the customer says the light was flashing after the no start or they say they didn’t notice the light, I will continue to proceed in this direction. The next answer I hear is usually the same and I believe is part of the cause of the B2960 code.

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GM Ignition Switch

“Wait to start? I just turn the key until it starts.” This is the biggest piece of the puzzle for me. Let me tell you how the Passlock(TM) lock cylinder works from Alldata. When the correct key is used to start the vehicle, a magnet on the lock cylinder passes close to the Passlock(TM) sensor within the ignition lock cylinder case. The magnet activates the security hall effect sensor in the Passlock(TM) sensor which completes a circuit from the security sensor signal circuit through a resistor to the security sensor low reference circuit. The BCM will measure the voltage on the security sensor signal circuit and compares this voltage to a previously learned voltage. If the voltage measured is within a valid range, the BCM will send a class 2 message to the PCM to enable vehicle starting. If the voltage measures is not within a valid range, a class 2 message is sent to the PCM to disable vehicle starting. Think about everything that happens when you turn the key on, all the modules are powering up, radio turns on, headlamps and light might come on, all the sensors are getting there reference voltages, etc. Now think what happens when you turn the key to crank, a lot of components are now turning off like the radio, hvac system, light, etc. and the starter starts to draw a couple hundred amps. Now think what happens when all of this occurs within a 1/2 second when the customer turns the key straight to start. Can you see where your voltages are moving all over the place in a very short time how the key code voltage may be off .2 of a volt and cause a no start and the B2960 code. Now lets say the magnet is a little weak or the key cylinder is a little worn and how this can happen very easily.

GM Key Lock Cylinder Tumblers Disassembled

Passlock Sensor Assembly

90% of my customers will be charged a diagnostic fee for what I have checked. I do a key relearn which involves 3 ten minute key cycles and I tell them to turn the key to on for a second or 2 and then to crank. I will never see them back for this problem again. The other 10% have a faulty key lock cylinder, forget to turn the key to on first, or have some other problem with the system. Of that 10%, a new key lock cylinder sensor will fix 95% of them while 5% of those 10% have a different problem. If I do not replace the key lock cylinder sensor right away because the customer wants to try turning the key to on for a second before starting first, I always let them know that if it does happen again where they get a no start, to turn the key to crank and then release without turning the key off, wait 10 minutes for the theft light to stop flashing, turn the key off 5 seconds to put the theft system into bypass mode. This gives them the chance to start the vehicle, not be stranded, and to save a towing charge so that I can fix the problem correctly for them. This is just my theory on this problem and this procedure continues to work for me.

Leave any questions or comments below. Thank you.


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Comments (34)

  1. DJ

    Thanks a lot for the info you saved me a lot of money and time… I’ll recommend this to anyone

    • RICH

      i have 05 saturn relay. the battery light came on as well as the security light then it went to battery saver mode as i made it off the highway the car died out minutes later. i put in a new battery and new alternator. and it starts right up and no more battery light but the security light is on steady. i tried to do the 3 sets of 10 minute thing but it will not get past the first set as the security light never goes off.to proceed. ??? help ???

  2. Liz

    I was stranded yesterday because of this…BUY the security light was NEVER on..the dealership did a ‘security code relearn’ And said it shouldn’t happen again..

    • Travis Dewitz

      Turn the key slow from position to position will help the most. If you are ever stranded again, try to start the car and then just leave the key on for 12 minutes. That will relearn the key.

  3. cb

    travis,
    i’ve had the key cylinder replaced on my 98 chevy malibu in 2003, 2006, 2010, and today. the car had 85,400 miles then and now has 240,000 miles. should this repair be considered routine maintenance or is there an underlying issue that has gone undetected?

    • Travis Dewitz

      They have been updated as far as I know. What brand are you putting in? I only recommend AcDelco or GM parts for that.

    • Travis Dewitz

      Do you turn the key on wait a second then to crank? That will help a lot. If you turn the key straight to crank you will have theft issues eventually.

      • jagnehparruinJanuary 10, 2012Hi Kim,Thanks so much for sharing your experience seeing the movie. I’m really glad you found it helpful & empowering. I think people’s reactions to the movie probably varied widely based on their own experiences and what they were expecting to see.

  4. Magnak

    Thank you for your support,
    I have this problem in Hummer H3, it waits for 10 minutes to start..

    What should I do to overcome this issue, I want to completely bypass this system. any support is much appreciated.

      • Billy

        There is a website that sells bypass kits for $400+ dollars but worth it if you have a defective car and don’t want to spend a bunch of money every few years on replacement parts… Use google to search for passlock bypass module.. Get the one with USA made parts as it is better quality….

    • Robert

      Do a search gor GM bulletin #26 may of 1999. How to bypass passlock gor remote start. It was gm’s slip shod idea back then, not mine. That is the cheap and easy way to solve a passlock problem. And no, you dont have to install remote start!

  5. Dean

    Hi there I have done every possible thing recommended from gm to resolve this no crank issue from all grounds removed and cleaned, to starter test and battery cables etc etc the puzzling part is when I try to jump the stsrter from the relay box under the hood it won’t engage. Was only able to get this work once. I can short it at the stater and it spins. Tried the relearn process but it doesn’t seem to work. So should I replace the key cylinder to rectify this problem. Any ideas are greatly appreciated as I have been in, on, under and over this truck for 4 days now in my driveway. Thanks in advance.

    • Travis Dewitz

      Sounds like you have a problem between the relay and the starter. Get a wire diagram and start testing from there.

  6. koleosho

    please I need ur help I have Chevrolet express van not starting I put computer to diagonise but was telling me lost communication with EBCM ,so please what should I do

    • Sam Silawanta

      Can u tell me how to reset a security light on 98 chevy express. The security light on and won’t start what can I do?

  7. Dave

    Sam,
    Do a key relearn first, just leave the key in the on position for 10 to 12 mins and the security light should go out.
    GM passcode is a tricky thing, I have ran into different things that can cause this issue everything from bad key switches to loose wire connections; people even overlook the ignition switch itself which go bad too.

  8. Becky

    what is the direction you go if the light comes on while driving but the car continues to start for a day or two after and then just won’t turn over at all. what would your diagnoses be then

  9. Emanuel

    hello friend I have a Hummer H3, the PassLock flashes and the car league after 10 minutes. it has happened three years ago, when I changed the ignition control and returned to work. Now again had problems since changed the ignition control and does not work, you could make a reprogramming with a specialized keychain and resolve?

  10. tengo una gran blazer año 1999 motor vortec y me prende las lus de segurida intermitente y le colococaron el scaner y sale el codigo 2960 en que me puede ayudar gracias amigo espero su repuesta

    • Travis Dewitz

      transalated – I have a great blazer vortec engine 1999 comprises the lus me intermittently Restraint and we colococaron the scanner goes the code 2960 that can help me thanks friend I hope your answer

  11. Ronda

    We have a 2001 or 02 Chevy Malibu. Code 2690 comes on should we do the relearn if so please tell me the proper way

  12. Tom

    Hope you could shed some light on my problem..2000 Malibu 3.1 v6 auto no start I have found that no power going to the fuel pump. I checked the relay and fuses all good 12volts. Also found that there is no injector pulse fuse good 12 volts. The car died when driving. I also have no communication with the ecm with my scanner.No anti theft light flashing I did replace the ignition switch ,crank sensors 7x and 24x,cam sensor still no start. full 12 volts every same as at the battery.

  13. Dave

    Hemm, I think I can help you with the ecm…
    The ECM will not respond if the acc fuse is blown on GMs so check that first.
    I don’t understand why you would replace the crank and cam sensors when you don’t have power to the fuel pimp,,,?

    • Tom

      I have checked all the fuses and they are good. I replaced the sensors just to rule them out I know I could test them with an ohm meter.

  14. Colleen Tillett

    My husband has a Tech 2, and my 2005 Chevy Impala gets a B2960 code. Have tried bypassing passlock by putting in a 500 ohm to 2200 ohm, in stages. He has spliced the resistor into the yellow wire and black wire on the passlock system. He can’t get the passlock system to work. He has tried all of the above.

  15. Prentice

    I have a 1997 buick lesabre custom. I stopped at a store, when come out. I tried to start the car it wouldn’t start. Find out it wasn’t getting gas. So, I changed the fuel pump and the fuel filter. Car started. But it sounded loud, rough and idled very high. Didn’t have this problem before the fuel pump and fuel filter change. Drove off the car strained before it changed to first gear. All the other gears work fine. After driving a while the fuel pump starts making a loud winding noise. And the tank makes at humping noise every now and then. What could be causing this to happen to my car. Could someone please help.

  16. Prentice

    I have a 1997 buick lesabre custom. The car also have a code PO121. Check engine light want go off and security light on. This is the same car that runs rough, sounds loud and strain to change to first

  17. Mark

    This morning when I started my 2006 Malibu Maxx up, the security light remained on. It drove normally with no problems. When I was at my destination, I turned the car off and let it sit for a minute. I then restarted it with no problems, but the security light was still on.

  18. Terry W

    I just installed a used in great shape low miles steering column from a 01 CHEVY Silverado 1500 into my 01 Chevy Silverado 2500HD utilizing the other trucks ignition and Key, won’t start up, starts to then instantly fails. I hooked up my Modis scanner and up came this common security code that lead me to this page. I’m waiting out the 12 minutes right now. Should I be installing my old worn columns ignition and Key? Thanks in advance.

  19. I have a 2003 Astro van with the symptoms you describe. Without intentionally waiting the ten minutes I went in the store to call AAA for a tow and when I went back to the car it started. The van has 240,000 mile on it should I just change the security sensor or the ignition switch?

    MikeC

    • Dave M

      Catullo,

      Have you ever had this happen before? If not you may have just not given enough time from the time you turn the key on till you start your van; try waiting 10 seconds after turning your key till you hit the starter.
      The computer stores the voltage information under the hall effect & pass-lock data. If you keep just turning the on and starting the van, the computer won’t store accurate voltage data. I am pretty sure the computer stores the last 5 voltage readings and if the voltage is always different, it will trigger the security on the computer and shut the fuel off…
      Here is one way to check, turn the key on and see if the security light is on, or just one quick flash then goes out. If you note that the light on more often then you need to give it more time for the computer to read it.
      If this happens alot then you may have to look else where.
      Good luck…

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