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Pontiac Grand Am Security Passlock Problems



  • pia2some,
    Did you get it to work? If so, we know that the 2003 is wired the same as the 2002.
  • I've been working ten hour days and haven't had a chance to work on it again. I'm hoping I'll have some time tomorrow evening. As soon as I get back to it I will let you know how it turns out.
  • I worked on the car tonight. Got the resistor in place using the correct wires this time. When I went to start the car, it did not start but the security light was flashing. I worried because the instructions on your website said that the car should start and then stall. Mine did not start at all. I left it in the on position for 15 minutes and then turned it off and restarted. It started right up and the security light is off.

    It's running now and everything seems to be okay. What do you think?
  • Looks like success to me!. Good work! Posting back with the pin layout of your connector was the key. You shouldn't have any more Passlock problems.

    Dick B
  • I cannot tell you how grateful I am for your information and knowledge on this problem. It made me sick to think of taking it to the dealer. So thank you.
  • The repair manual for the '97 is in 2 volumes; I have the volume that does not have any diagrams, only instructions. The '98 is in 3 volumes, again,no gots the one with diagrams. I left them with the gf that has the car, & we aren't seeing one another currently. lol
  • my 99 Grand am has been great! over 230,000 miles now and just replaced the alternator couple months ago, first repair done to it. everything else still original.
    Well, now the car got caught in a flood :(
    I'm fighting to get it running again, the Airbag computer and the BCM was under water and someone told me the lights were flashing on car while in water, so pulled the BCM and its bad looking, like years old green corrosion and rust everywhere.
    I removed the BCM.
    got fuel tank cleaned out fresh fuel, car starts and stalled in seconds, once it stayed running, sounds great! then doe not start again, hmm.
    I had it running for at least a minute, but I turned off because fuel return line was filling up a jug. can the car run without the BCM?
    just found out about the security and its relation to the BCM.

    Turn the key on, no Security light, try to start it and it stalls, then the security light is on steady. the security light does not go out after 15 min wait. of course the BCM is not connected.

    any way to bypass BCM?
  • Bypassing the BCM would be a daunting task, because it communicates with the Powertrain Control Module over a digital buss. Here is the description of what it does, regarding the Passlock system.
    "The BCM contains the logic of the theft deterrent system. The BCM provides the battery positive voltage to operate the Passlock(TM) Sensor. The BCM also measures the voltage of the security sensor signal circuit. The voltage measured will indicate whether the Passlock(TM) Sensor has been activated and whether the resistance value from the sensor is a valid value or the tamper value. If voltage measured is in the valid range, the BCM compares this voltage, voltage code, to a previously learned voltage code. If the voltage codes match, the BCM sends a class 2 message containing a password to the PCM. If the voltage codes do not match, or the voltage is in the Tamper range, or there is a circuit fault, the BCM will not send the correct password to the PCM, and the vehicle will not start."

    So, you see, the BCM translates the analog voltage from the passlock sensor into a coded digital signal to tell the Powertrain Control Module that it's OK to let the engine run.

    Your cheapest alternative is to get a salvaged Body Control Module, take it to a GM dealer and have them re-program it for you. Note that everything to do with the body of the car is controlled by the BCM.... I.E. The Power Door Locks, The Trunk Latch, Headlights, Taillights, Brake Lights, Door Chimes, Horn..... You just can't drive the car without it.

    Before going to the dealer, make sure your connectors are corrosion free. Clean them with a mild solution of naptha soap in distilled water, and then rinse with denatured alcohol. Good luck.

    Dick B
  • Thank you for info, it makes sense.
    it just threw me off when the car actually started and ran, must of been luck.
    now I just have to wait till the new BCM arrives.

  • burdawgburdawg Posts: 1,524
    These problems are probably just the tip of the iceberg after flood damage. With that many miles I recommend you start looking for something else.
  • Burdawg is right. You will likely need to replace your PCM as well. I'm curious why you haven't filed a claim with your insurance company and just had the car towed to a dealer and repaired. Sure, you would have to pay the deductible, but I don't think I would try to repair flood damage on my own. Just too many things that could be wrong.
    Dick B
  • Is the 'passlock' issue related to the key? And how can I figure out that my issue is in fact a 'passlock system' issue or rather, say a bad starter?
  • The passlock issue is related to the key in some vehicles. Read all the information at:
    To find out if you have a passlock problem, as opposed to a bad starter.
  • a bad starter will have battery voltage at the small solenoid terminal when the key is being turned. Sometimes it will turn the engine over if the main body of the starter is being rapped sharply with a hammer while the key is engaged. This would be due to a flat spot in the armature.
  • i was having the same issue and after doing the relearn procedure my car started fine but none on the gadgets on the dashboard work at all (turning lights, fuel tanq, speedometer)... i went to the dealer and $120.00 later they couldnt figure out what is wrong with it :(
  • When you bring a car to the dealer with a problem, and they cannot fix it, I would think they have a moral obligation to release your car without charging you. I find it hard to believe that any reputable dealer would charge you $120.00 for doing nothing. If I were you, I would take your car to another GM dealer, tell them what happened at the other dealer, and ask them if they would please direct you how to lodge a complaint against the one who gypped you. Then see if they offer to actually repair your vehicle.
    It's normal for the dealer to charge for diagnostics, but when the diagnostics turn up nothing, and the problem is still there, that reveals that the diagnostics they performed was ineffective... a sure sign of dealer incompetence. I'm assuming that you described your problems and demonstrated what was not working when the write-up tech checked you in.
    Good luck
  • gmcustsvcgmcustsvc Posts: 4,251
    I apologize for your frustrations. Did the dealer involve Technical Assistance? Have you spoke with Customer Assistance? I look forward to your response.
    GM Customer Service
  • Im workin on a 2002 grand am for a friend of mine. I had to reset the passlock system about 4-5 months ago and it ran great. until today. he replaced the turn signal bulbs earlier today and now its fubar'd. the security light aint comin on but it'll start and run for about 2-3 seconds and die. i can hear the fuel pump runnin so i know its workin. the fuses are all good and when i take the battery terminal off and reset the computer, that doesn't do anything. any help would be greatly appreciated
  • I am so glad I found this because I am just lost, I need help. My 2001 Pontiac Grand AM(146,000 miles) won't start right now, I been having problems since Feb 2011. For some odd reason when I cut the car off the car seems to think the keys are still in it so it would make this noise as if the keys are left in(ding, ding, ding) and I would ignore the noise but when the car sits to long, unfortunately this drains the battery and I would need a jumpstart. I am so tired of getting jumps and no mechanic can fix it, I have spent money cause mechanics have told me, it was my battery at 1st, then my alternator, then my fuel pump, now what? It seems like they were just guessing. So right now if I jump the car, it will die immediately and the noise comes on as if the key is in the ignition, when it's not and now the car is just sitting, when i try to start it, nothing happens as if the battery is dead, I just don't know what to do. I had these lights on, Security, Engine Light & service engine soon but when I went to see why the engine light was on nothing read. Does this seem like a Passlock issue? Another mechanic said he can't fix it and that I would have to take it to a Dealer and then another one said I may need to replace the entire engine and something else about the tumblers in the ignition. Can someone please help me?
  • lovemygrandamlovemygrandam Posts: 330
    edited October 2011
    Your initial problem was NOT a passlock problem, but now that the SECURITY light is on, You may have the passlock problem plus another one as well.
    The chime remains on all the time for several possible reasons, including
    * headlights on
    * Key in Ignition
    * interior lights on

    It sounds like you may have a shorted switch in your ignition module. If you follow the diagnostics in the following two figures, you should find out whether or not that is your problem. Previous postings here have referred you to my website, where you can find the location of the Body Control Moudle.
    Pay particular attention to steps 3, 8, 10, 12, and 14, which refer to the key warning switch. I've also included a diagram of the audible alarm system to help out. If you can't do the diagnostics yourself, any good service technician should be able to find and fix your problem if you print out this post and bring it with you. Please let me know if this helps...
    Below is a schematic of the audible alarm circuits. If you right click on the diagram, you can view a larger version of it.

    You may also find these diagrams useful.
    BCM Schematics 1
    BCM Schematics 2
    BCM Schematics 3
  • Ok, so a few months ago my 01 grand am wouldn't start at all so my dad & i did the passlock rewiring from Bergerweb and it did not work. well, i put off dealing with it for awhile because i was so frustrated so i just this week had it towed to a chevy dealer. i figured i'd prob just need a new bcm but wanted them to check it just in case there was something else going on. well, today the mechanic called and said they were able to do the relearn so they didn't think it was the bcm, they thought just the passlock sensor and connector stuff needs to be replaced. of course, this will cost about $500. they also said they had to bang on the bottom of the fuel tank to get the fuel pump to kick in, so of course they want to replace that as well. all told, the charges would be approx $1200!! i was wondering if anyone had any ideas about where i should go from here. is it worth doing any or all of these repairs? i can't believe that the car is really even worth $1200. ugh.
  • If the car was sitting for "a few months", it is no surprise the fuel pump needed to be kick-started.
    I won't get started on the issue of how financially needy the dealers act ( worked there for decades) , but if the relearn worked, then save your cash. I replaced the passlock sensor AND instrument panel for under $60 with used stuff & my GA always starts now.
    And most towns have repair shops that have ex-dealership mechanics who pride themselves on being car fixers rather than parts replacers. Need to call around to find the honest and competent ones. They are getting rarer every week.
  • well, i'd prefer not to have to pay to replace the fuel pump but you think i can replace the sensor myself? i asked the dealer if the car was drivable since they did the re-learn but he said it wasn't since they had to pull it apart and do some sort of "trick" to get it to work. so, i guess i'd probably have to have it towed somewhere else. if i replace the sensor myself (or have a non-dealer mechanic do it), where would i find the parts (junkyard?) and do i have to have the car reprogammed afterwards? i'm still not 100% sold on the idea that it's not the BCM, since we tried the bypass re-wiring thing and it didn't work. i just want there to be an easy(ish), not crazy expensive way to get this car fixed. haha.
  • If you did the bypass as per, and then later, the dealer was able to get the relearn process to work, then you should be all set forever, unless you "undid" the bypass before having it towed to the dealer. If that's the case, then the BCM is OK, and you made a mistake when you did the bypass.... otherwise the relearn procedure would have worked for you, since we know that the dealer got the BCM to relearn the resistance of the sensor module.
    There is no secret stuff inside the passlock sensor module. It consists of resistors, a hall-effect transistor, and a three-pin connector. When you cut the yellow and black wires, you take it out of the circuit and replace it with a resistor, which eliminates the variation in value caused by the connector pins and the hall-effect transistor. The BCM then will learn the value of the resistor you substituted into the circuit, and since the resistor is a stable value, you will never have the passlock problem again..... Unless.... you have corrosion on the pins of the center connector of your BCM.
    In other words, you have ALREADY replaced the Passlock Sensor.

    Perhaps the reason your car would not start after you did the bypass, was because of the fuel pump being stuck. Then you re-wired it to the original configuration, took it to the dealer, and they managed to fix (temporarily) both problems?

    Now that your fuel pump is working, try the bypass again and see if you can get it to relearn, and turn out your "Security" light forever.

    Dick B
  • ok, sorry that i'm a little dense with this stuff, but i just want to make sure that i understand what's going on and what i should do. i'm really glad that you guys think the fuel pump problem is just because it sat untouched for so long (~ 6 mos.) and not really because it needs replaced.
    as for the passlock stuff, we did undo the rewiring that we had done before having it towed. so, you think that if i have them put the car back together, tow it home (they said it wasn't drivable without getting the sensor replaced), redo the sensor bypass, it should work? when we did the bypass originally, we did the version where you go through the glove compartment, and we double checked the BCM, which seemed to be free of corrosion and/or water. after doing the bypass and doing the longer relearn technique, the security light never went off and the car wouldn't start. if i do the bypass again, and it still doesn't start, do i need to have it towed yet again (3rd time) and have someone do the dealer relearn? how do i get the dealer/technician to do the relearn without wanting to do the full passlock replacement?
    i'm sorry for all the probably obvious questions, but i really want this to get fixed quickly, easily, & (reasonably)cheaply. i really do appreciate all of you guys' advice and help!
  • My advise...
    At home, make the bypass module I describe in the first few steps of Take that module with you to the dealer, and do the rest of the mod yourself in their lot. Then have them do the relearn.
  • Im going to give the bypass a try and see if it works. I've been doing a lot of reading since i figured out, through replacing the battery and starter my self, that there was this problem.
    Ill keep this post updated to see if all the bypass and re wiring tutorials work for the 2005 model.
    all i have seen is for cars older than 2004 so I am not quite sure if it will but ill still check out the BCM and buy some resistors to try and by pass it. I might use a terminal through the radio to prevent the need of soldering any wires while I'm stuck at a gas station.
  • everything went fine and only took about an hour total with some tinkering. the 2005 model has the same yellow,black,and white ( but my white cable was dirty and looked almost creamy yellow, a bit confusing. )even checked the BCM and had some mold on the A6 part and cleaned it all up. it was only surface mold, none made it into the black box ( car flooded once so this makes sense. )
    but all in all it was easy. :shades:
  • Hey Guys,
    I have completed the latest bergerweb passlock fix, the no-soldering method.
    So the car ran great with no problems for a few months and the security light is off and still is.
    Lately the car began to act up again and the car would crank and crank but no start. After a about 10-30 minutes of doing nothing and letting the car sit it would kick over and run fine. This problem recently has become more frequent.
    So where do I go from here? any suggestions would be much appreciated.
    The car in question is a 2002 pontaic Grand AM GT.
    thankyou in advance.
  • I would suggest Replacing the fuel filter first. Then check the fuel pump. If the problem occurs when the vehicle is either very cold or very hot, check the ignition modules. I'm assuming that the "security" light is not lit.
    Dick B
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