Passlock II SECURITY light and truck won't start!

OK, since the last time anyone seems to have had this problem was about six months ago, I thought it might be time to start a new thread.

I definitely have this SECURITY / Passlock II issue as well on my 98 Yukon. My situation may be a bit more unique than others though. Hoping some of you can chime in on whether I even need to replace my key sensor since it is already bypassed with a Directed Electronics module (part of my remote start installation).

This morning, I got the dreaded blinking SECURITY light and fuel cutoff indicating a bad Passkey II value sent to the computer. Despite all efforts, I could not get the truck started and had to hitch a ride to work.
About two months ago, I had tore down my remote starter and bypass module wiring. I confirmed that the ignition yellow wire had the same resistance value as my bypass module. I then proceeded with SOLDERING all connections, thinking my problem may have been related to faulty wiring.
The truck ran fine since then and I really believed I had resolved this. However, recently I'm being haunted by this.

So, my questions here are:

Is there any way to confirm without a doubt the resistance value the computer is programmed with outside of testing what the ignition switch has? Maybe I'm off a few ohms...

How does the ignition switch come into play when a bypass module is installed. Isn't that the point of having one - so you don't have to rely on the ignition switch anymore?

If my bypass module is 'dialed-in', why am I still getting a SECURITY light!?

I feel your pain. I went through the same thing. I even had a remote starter installed to, all connections were soldered as well. It is in the ignition lock housing. It is considered a wearable part, too much wieght on your keychain is the biggest reason for this to happen. You cant just replace your lock cylinder like the older trucks/cars. When I did mine, I replaced both parts because I did not want to take any chances. This was an ongoing problem that left me stranded as well as my family. This started in July of 09 when moving down to NC. It did it very infrequently until 07/10, then It started to happen almost every week and it came to a point where it happened on a daily basis. Waiting times ran from ten minutes to over an hour for it to start. Sucked to say the least.

This is my thread with part numbers for the parts needed.
http://www.gmfullsize.com/forum/showthread.php?t=199600

Good luck, if you need any info, dont hesitate to ask.

Thank you. This morning has been all about reading your link. My truck is sitting on a charger right now because after extensive attempts to get the truck to re-learn the Passlock code, my optima battery had just about died.
I did read in other forums that I could disassemble and clean the six contacts off (some said theirs were burned?)
Any chance you know where I can get a picture of these parts and maybe how exactly to remove them? I just want to know what I'm in for if I drop another $300+ into this money pit.

http://www.gmfullsize.com/forum/showpost.php?p=4120063&postcount=42

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Just found this site. Perhaps a way to bypass the Passlock without purchasing an aftermarket kit/alarm add-on. Seems like it would apply to all vehicles, but perhaps those of you out there with more experience than I can confirm this.

http://www.bergerweb.net/PasslockFix/index.shtml

tlamot01 said:

Thank you. This morning has been all about reading your link. My truck is sitting on a charger right now because after extensive attempts to get the truck to re-learn the Passlock code, my optima battery had just about died.
I did read in other forums that I could disassemble and clean the six contacts off (some said theirs were burned?)
Any chance you know where I can get a picture of these parts and maybe how exactly to remove them? I just want to know what I'm in for if I drop another $300+ into this money pit.

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That sucks about your battery, it should only take 30 minutes to do the re-learn.
I'm sorry, I'm not having any luck finding those images. Get in touch with GMPartsdirect.com, not only do they have the best prices they should also be able to get you images of each item or maybe a schematic.
To be brutally honest, its a PITA to do. You have to remove your steering wheel, airbag, the steering wheel column cover, hmm I'm sure I'm missing something. You'll also need a special tool to remove the ignition lock housing, I made one, if you need it let me know. The ignition harness was a lot easier but, you still have to reach into pretty tight places and get in uncomfortable positions.
It took just about a day from start to finish.

tlamot01 said:

Just found this site. Perhaps a way to bypass the Passlock without purchasing an aftermarket kit/alarm add-on. Seems like it would apply to all vehicles, but perhaps those of you out there with more experience than I can confirm this.

http://www.bergerweb.net/PasslockFix/index.shtml

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I am not too fond of modifying electronics, regardless of the situation. I'm sure others are but, me, I'll stick with the books and do it right.

If you need anything dont hesitate to ask

OK, after three attempts to 're-learn' the Passlock password, the truck started. Now my security light stays lit (for how long I don't know). This morning, the truck fired right up even with the lit security light.
How long I can go without having to do this again is anybody's guess.
The only positive thing about this is that the entire fix cost me $0, and very little pulled hair.
As long as this re-learn procedure continues to work, I won't thing about modifying the wiring beyond the existing Passlock bypass module that's already installed.

PS. I'm waiting on a response from GMPartsdirect about those two items. I will post what I get.

The re-learn is for after you install the new parts. Then you do the re-learn once and you wont have to do it again. If you do the re-learn before replacing the parts, you will be doing it quite often.
The first time my truck stalled was in July of 09 and finally broke down and fixed it one year later. To give you an idea, it would stall on start once a month maybe for a few months. Then it would stall once a week, then twice a week, then every day until it started happeneing several times a day. The suck part is, you never now when its going to happen.
I guess my point is, do it once and do it right. I would hate to see someone else go through what I went through. I no longer have any hair

Modifying the harness is a little sketchy to me. It is there for a reason, thats how I think of it. Now that its fixed its not a worry/problem.

Did you search those part #s on GMParts? Not bad prices. I believe it was under $250 for both.

So again, I'm going back to the bypass device that is already installed. Isn't this supposed to do exactly what the new ignition sensor already does - mimic the resistance value that the hall-effect generates when you turn the key? So if the bypass is in place and working (required cutting the yellow wire, so I don't even see how the key comes into play at all), then why am I even getting a Security fault condition at all?
Maybe there's something about this system that I'm missing...
Without bypass: Key turn creates resistance value read by hall-effect; sends resistance value to BCM; BCM confirms value; sends 'password' to ECM; allows fuel injectors to operate.
With bypass: Bypass module sends resistance value to BCM when +12 is sensed on IGN2 (usually initiated by remote start sequence or key is turned in cylinder); BCM confirms value; sends 'password' to ECM; allows fuel injectors to operate.
^^
Right? If this is true, then maybe my BCM is forgetting the resistance value? I just don't see how changing out the hall-effect sensor in the ignition switch is any different than just mimicking the existing value through a bypass module, especially since the yellow wire has been cut.

(My bypass module is non-programmable and requires the cut wire unlike recent units that I've researched that simply tap into all three of the Passlock wires - although should still achieve the same result...)

---------- Post added at 01:42 PM ---------- Previous post was at 01:37 PM ----------

PS. I still have my ignition switch fully exposed. I'll take some pictures and post them here. Maybe since you've already done this, you could point out what exactly needs to be replaced or cleaned.

It was a while ago, I dont remember everything. I try to forget as much as I can about that whole situation, hah.

The easiest way to explain this is. Its a wearable part. The part that the key goes in has a magnet, it wears over time, and the security system does not recognize the key, hence the security lite. Thats when I was saying more wieght on your key ring causes this problem. Like the older trucks, you used to be able to remove the cylinder and be done. Now, you have to replace the whole housing because GM decided to add the security device to the ignition system. I replaced my ignition harness as well to be on the safe side. I wanted everything to be back to factory spec.

What year is your truck?

OK, I did get a response from GMPartsdirect

Dear Mr. Lamothe,

Part number 26049449 is for the ignition cylinder case, which includes the passlock sensor.

Thank you,
Adam Wilkins.


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Re:
According to many forums, I need a new Passlock sensor. I\\\''ve been given the part number: 26049449. You list it here, but there is no diagram or picture. Can I get this info to confirm I\\\''m buying the part I actually need?

Symptom: Security light blinking and engine refuses to start even after the long-tamper cycle of 10 minutes has completed.

-TiM

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So it appears that they either don't have a diagram or just didn't bother to send me one. I took some pictures of my exposed steering column. Perhaps you can point out what changing part 26049449 actually involves.