PassLock replacement problem

Per mechanic codes the 2 parts of the ignition sensor need replacing. However, 1 of the 2 parts is back-ordered & not available–dealer or 3rd party. Is there a way to mechanically bypass the PassLock system to get around this problem? 2000 Silverado 2500 4WD.

In my experience… no. Depending on the system, most systems disable the fuel system and the ignition system. The fuel system can be bypassed to get the fuel pump operating but the problem is in getting the ignition system working.

If the passlock module sees the proper signal it will send a signal to the PCM to allow the car to start. The PCM operates the ignition and fires the coils at the proper time, that part of the system can’t be by-passed.

So I haven’t found a way to by-pass it but that doesn’t mean it isn’t impossible. I would check at some shops that specialize in electrical problems and see if they have a way to by-pass it.

Here’s what I don’t understand. If the passlock module(s) are REMOVED, then there shouldn’t be anything sensing to disallow an ignition or fuel system?

The PCM is the problem, it has to see the proper signal or it shuts everything down. You can remove the module but the PCM still has to see a reference signal so the engine will start.

I have tried. I can get the fuel pump to run and get fuel pressure to the injectors. The PCM controls injector pulse and spark, without the PCM they don’t operate.

The question is… what reference signal can be substituted to get your PCM to operate? I can’t find that information. If you could find out what the reference signal is for the PCM in your vehicle you could put that signal to the PCM and it should work.

It’s probably information that only the engineers at GM know. Again I don’t think it’s impossible I just haven’t found the answer yet.

There is enough PassLock bypass info on the web to fix any problem. Just how good is your mechanic with passLock systems?

Yes, there is alot of information on the internet but from what I have read the results are mixed at best.

There are aftermarket modules available but be careful of what you find on the internet, it’s not always what it claims to be.

I am not talking about buying anything, I am refering to information about how the system works, this information is a key in understanding how to fix it.

Take dowm some phone numbers and give these companies a call, you may find you have much to learn.

Perhaps all the OP needs to do is a “key relearn” has he tried this? does he know how? this is the type of information that will keep your money in your pocket. Stop blaming the internet, it is only the messenger.

Is this the same type of security system used on the Cadillac Escalade? If yes, then someone knows a way around it, these do show up on the frequently stolen list of cars.

I know how the system works, oldschool. As I said it is not easy to by-pass, I haven’t had any luck doing so and I KNOW how the system works. Maybe you could relate your experience in by-passing the system.

The OP asked how to by-pass it. If you can read you would know that he has already had it diagnosed but the parts are on back order.

willey, just what exactly is the problem with the PassLock system? what is the status of the “theft” light? has the OP tried a “key relearn” if you knew how the system worked these are the questions you should be asking and you are not so you don’t.

Just a hint for you willey, no bypass techniques will work when the vehicle is in theft mode, you must get it out of theft mode for the common bypass methods to work, I am sure you knew this :slight_smile:

Yeah the OP said “per mechanic” and I question the skills of the mechanic making the diagnosis because HIS customer is comming to CarTalk for advice. If the mechanic was any good HE would be giving HIS customer answers, not sending him to CarTalk.

Willey, you say “you want to help the OP” but you are not asking the right questions, starting with asking the symptons, and verifying if the man making the diagnosis is qualified.

Wiley after you have been around a while you will learn not to accept other peoples diagnosis on issues such as this one, you must do your own diagnosis, and when doing it over the internet you will learn that means asking the right questions.

After answering the OP’s base question,in my way, by telling him to look on the internet for the volumes of data about PassLock (more that I could ever know) I asked “just how good is your mechanic”. Many mechanics just don’t have it together when confronted with PassLock issues and make diagnostic mistakes, you learn this from the experience of working with mechanics and systems like PassLock, and this experience is something you are clearly lacking.

wille it’s YOU with the problem,your the one calling people names, I am just pointing out proper diagnostic procedure, you are the the hijacker here.

OP don’t ignore my advice as I am sure I have much more practical experience with passLock than willey, and beleive me when I tell you mechanics make diagnostic mistakes when working with PassLock.

I took a GM communications class, and as I understand it a magnet of a specific strength passes by a sensor at a predetermined distance, intentionally varied from car to car and is “taught” to the BCM in the factory, when the key is turned. The BCM Then sends a signal to the PCM saying that it is OK to turn on the fuel injectors and such. It apparently works differently on on some models, as some you can start, but they will stall soon after. So the issue seems to me that you either have to find a way to trick the BCM into sending the signal to the PCM, or trick the PCm into thinking that the BCM IS sending the signal. My factory manual gives no info on how to do this, just how to replace parts and relearn key signal. So your best bet is to find a good car thief and ask him, down side to this is then he will probably steal YOUR car. Good luck

willey, there are three implementations I am aware of for the various configurations and vintage of PL/PK. A simple 30Hz or 50Hz, 50% duty cycle pulse train in the early versions and a serial password over the data bus in the latest. The latter obviously being the more difficult to defeat.

Thanks for your post. It’s what I was trying to relate to the OP until oldschool came on with his condensending attitude.

If the PCM can be tricked then that is a viable option for a by-pass but as you stated finding that information is hard to come by.

oldschool read his post, it’s a great piece of helpful information.

I’ve also read about using resistors to get the proper reference signal. It would be interesting to try but I don’t have the time to invest in experimenting with it.

From what I’ve read about aftermarket systems and by-pass resistors it has limited success and other problems seem to surface. Many of the by-pass modules only work with a remote start system and most won’t work if the car won’t start to begin with because of a passlock problem.

It’s a dumb system, you should have the option to completely disable the system if you don’t like it.

Willey you need to attend a real technical course on PassLock then you will be able to have some credibility when you lable something “helpful”.

I need to clarify a few things regarding my initial post. First, the mechanic obtained several trouble codes from the truck. He plugged those codes into a computer program he has to interpret the codes. I believe it was 2 of the 3 codes that were specific to the passlock. There were 2 parts required as a result for replacement (I can get both the codes and part names Monday). GM had one and the other back-ordered. He tried several 3rd party dealers for the back ordered part and all had the same response–not available (indicating that one company is making the part for both GM and 3rd party). The message he left on my home phone late Friday was that he had ordered the one he could get from GM and would try on Monday to bypass the second part–if he could. This was sounding very shaky. Obviously the information I’m giving you is incomplete and I will have more information Monday afternoon or Tuesday. I decided to post the problem here since I’m very concerned that the necessary part that I would be willing to purchase is simply not available (hopefully just at the moment–but even in that instance I do not know how long ‘at the moment’ is). My mechanic is honest and good for ‘normal’ mechanical stuff. If the part if not available for an extended period (and I sure would like to determine the time frame for sure) and my mechanic is unsuccessful, I need to have a plan B. Having the truck towed from Evergreen, CO to the Car Talk guys garage is not in the plan (ha, ha, ha)!

I also would be concerned if the diagnosis was being done by a mechanic good for “normal” work but not trained in the tricky PassLock system. Simple diagnostic errors and procedures can cost you a lot of money, like trying to do a key-relearn with the trucks door open, it won’t work but many mechanics don’t know this.

OP what is the ststus of your theft light? does the car crank but quickly die? have you tried a key-relearn? Is your mechanic working with a scanner that has all the capabilities of a Tech II? (GM Dealer scanner). If not he is working with a handicap,not impossible but surely a handicap.

From memory, the security light was coming on periodically for reasons that I didn’t and still don’t know and didn’t pay much attention since there was never a consequence that I could relate to the light at the time. I’m fairly certain that the mechanic is not working with the latest and greatest. However, as I mentioned previously, the error codes that he did get and entered into the computer (which was most likely internet connected to a mechanic’s program) returned codes specific to the passlock. Further, the symptom as described below matches a symptom of the passlock returned by the computer.

The truck has displayed the problem very intermittently starting this past August with the first instance, another last week and then the final one requiring towing a few days ago. When attempting to start the truck, the engine responds as if the fuel pump is dead–cranks, doesn’t turn and dies. of the 3 problem occurrences, the truck started after a period of time on occasion 1 and 2. On the last occasion I left the truck and returned in the morning and it didn’t start. It did start for the mechanic once the truck was towed to the garage.