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Discussion Starter · #1 ·
99 Suburban 1500. Passlock system intermittently causes the burb to not start - perhaps you've seen my post in the "member intro" area - " New from Texas - Haunted 99 Suburban" ??? I am hoping someone here might know of a work-around. We have yet to ID something that causes the passlock system to think it is being stolen, and cuts off the fuel flow. The only work-around that seems to work every time is to wait one full hour and then try, and it always starts. But waiting one hour is not very practical 99% of the time. I read someplace that when it malfunctions, you turn the key to the "on" position, and wait a few minutes, till the "security" light on the dash goes out, then it should start. But, wouldn't you know it, I can't get it to malfunction, so I can't test that work-around. Anyone have any ideas? Thanks.
 

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Discussion Starter · #2 ·
So .... I guess no one else has this problem? Or is it that everyone else has just fixed it and didn't need a "work-around? It's been 2 weeks, and I still can't get it to malfunction. Other factors have prevented being able to take it in to a dealer. Oh well....
 

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There is a way to disable the system, but for the life of me I can’t remember how to do it.

I would check with a dealer near you to see if it may be just a dirty or malfunctioning key. I don’t know about your year but the older ones had a resistor in the key. Very expensive to get copies made as I remember.

I have to hunt down some other things tonight so I will look for what I can find about this.
 

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[media]http://www.aatecusa.com/ata/downloads/passlock.pdf[/media]

Gives the system parameters.

You can check the system with a scanner.

If I remember right, and I could be wrong you have to find out what the resistor value is in your key and substitute that same value resistor in the ignition circuit. But I am still looking for better info.

Aha here we go.

[media]http://www.gmupfitter.com/publicat/bull/bull26.pdf[/media]


Warning, Will Robinson
Very complicated.
 

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Discussion Starter · #5 ·
Thanks. I'll read those two items and see what I can work out. I'm still hoping for something definitive in the way of a work-around. My experience with intermittant vehicle problems is that untill they cease to be intermittant (or malfunction ALL the time), they are very difficult to diagnose. Earlier this week I met a guy who directed me to a shop here in Houston, that speciallizes in steering column problems. He claimed they had lots of experience with GM's systems, and were very good at diagnosing problems. I'll give them a call soon, and see where that leads. Thanks again.
 

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Do you have the keys with the visible contacts on the blades? Sorry I don't know how else to describe them. I don't know a whole lot about the passlock system but I had the same problem in my 97 malibu i used to have and I have heard of others having the same issues with other GM vehicles from around the same years.

Malibue would do the same thing. Put the key in and all of a sudden the theft light is on. Had to wait 30 minutes to an hour most times, sometimes only 15 minutes. Not a good thing when you are a service tech who drives 500 - 700 miles a week around the city of Houston. Last things I read about them ended up being bad ignition lock cylinders.

I also had a friend that was having the same kind of problem with her Isuzu Axiom and it ended up being dirty keys.
 

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Discussion Starter · #7 ·
No, but I know what you are talking about, my folks gave us their '92 Buick and it's ignition key has a small black rounded rectangle, with an exposed wire in the blade, about midway between the tip of the key and the head. The '99 burb has no such chip, just a smooth blade with a blck rubber head.
 

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I had a similar problem in a 99 venture. I had a set of keys made at a local key shop (not GM) and the keys worked great for a few days then started locking the systems. Service guys at GM told me I could use the factory key and it would reset the system. So my thought is try a different key. If I recall my keys were not too much for replacements. But I might be thinking of a different vehicle. Either way Good Luck!
 

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Discussion Starter · #9 ·
We inherited the burb when my DW's parents passed away (fall 1999 the burb was 6 mos old). The three keys we got all looked identical and all had black rubber heads - so we suspect that all are "factory" keys (but don't know for sure). I had a key made at the hardware store - plain steel, no rubber head. This plain key worked fine for me for 6 years, though I drove the burb infrequently, my DW drove it every day. When we started having problems with the burb, we suspected my plain key, so we stopped using it. Over time we we eventually stopped using two of the other keys and only used my DW's key. Very long story shortened the problems are so intermittant that we don't know anything, key-wise, for sure. Right now, it has worked fine for a month, DW has driven it with her key, I've driven it many times using my key - I can't get it to malfunction. Thanks for the input.
 

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99 Suburban 1500. Passlock system intermittently causes the burb to not start - perhaps you've seen my post in the "member intro" area - " New from Texas - Haunted 99 Suburban" ??? I am hoping someone here might know of a work-around. We have yet to ID something that causes the passlock system to think it is being stolen, and cuts off the fuel flow. The only work-around that seems to work every time is to wait one full hour and then try, and it always starts. But waiting one hour is not very practical 99% of the time. I read someplace that when it malfunctions, you turn the key to the "on" position, and wait a few minutes, till the "security" light on the dash goes out, then it should start. But, wouldn't you know it, I can't get it to malfunction, so I can't test that work-around. Anyone have any ideas? Thanks.

This is true. Turn the key to the start position & wait 10 minutes. If you don't have kids making noise anyway, turn the radio off & listen. You can actually hear the thing unlock.

Anyone out there know what to cut to by pass the PassLock system completely??? I guess this is a common issue. :happy:
 

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Had the same problem with my daughters malibu a few years back.If I remember right, you turn the key on/off 3 times then wait for light to stop blinking.
 

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this is a weird problem i have from time to time with my 99 silvy. If you ever find a solution to it could you please share it with us. Some people say fiddling with the power lock switches fixes it although i cant confirm it. I do know it is annoying and always happens at the worse times.
 

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do you have a magnetic chip key for home or office or a speed pass on your ring this does interfere sometimes
 

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Discussion Starter · #15 ·
do you have a magnetic chip key for home or office or a speed pass on your ring this does interfere sometimes
On my ring I have: an RFID key and remote for a 2001 Ford Taurus, and a resistor type ignition key from a 1992 Buick. My wife has only the remote for the Sub, and keeps her remote and RFID key to Taurus on a separate keyring. Neither of us has a speedpass of any kind on our keyrings. Thanks! -Dave
 

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Discussion Starter · #16 ·
Well it malfunctioned (for the first time in a long time) over the weekend. I forgot about the earlier post saying to turn it on and off three times then wait, so I tried what I remembered: turn it to the on position and wait for the security light to go off. I checked it about every 5 minutes, and it took between 20 and 30 minutes, and when we noticed the security light off, my wife turned it to off, removed my key, put her key in, and it started fine. Next time I'll try the 3 times thing, and see what happens - if I remember - the darn thing is so intermitent - Nov '07 was the last time it messed up. If I could GET it to mess up, I could test solutions. So frustrating!!

I re-read the two items that "84fiero123" posted, and I'm thinking about installing the cutoff switch. It sounds like it will only work if you anticipate having a problem and open the switch prior to shutting off the Sub, and not necessarily if you wait till it won't start, then open the switch, but who knows? It can't work any worse than it does now, can it? The Sub KNOWS when we are camping and thus far from home, and picks that time to mess up, so we'll only open the switch when we are far from home to out manouever it (I'm only half kidding here!!!). Thanks for all the help, I'll post any results to pass the info on to others.
 

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If you want to see if it can be bypassed check with a place that installs aftermarket remote starts.
Thats what they do to get the car to start with no key in the ignition.
 

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Discussion Starter · #18 ·
An Update: another camping trip, another malfunction. We were preparing to leave, and the Sub wouldn't start. This time I tried #2WA (work around #2 - turn it on and off 3 times, then try to start it) and this worked! WOO-HOO!!!! I have not had time to try to install a bypass switch - if this WA works consistently, I probably won't.

To summarize the WAs (work arounds):
#1WA - exit vehicle, lock and unlock with remote, enter vehicle and try to start. Results: this did not work back in May.

#2WA - turn on and off 3 times, then start the vehicle. Results: this worked this time, but it seems like I tried it once before and it didn't.

#3WA - turn on and leave on untill security light goes off. Results: this worked back in May, the downside is it took 20-30 minutes of waiting.

#4WA - exit vehicle, wait one hour, try to start. Results: this has worked every time, the downside is waiting an hour.

Will update as more stuff happens. -Dave
 

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I don't know if this helps but I know that the ignition switch contains some wiring harnesses that plug into the ignition lock cylinder and one of those is for the passlock system. There is a TSB (not a recall, however) out for faulty ignition switches and your problem could be related to this.

I had a problem with my gauge cluster malfunctioning which was also a symptom listed in this TSB so I replaced mine with one from Autozone and ever since it has been problem-free. For a first timer with a factory service manual, it is about a 3 hour job. You have to disable and remove the airbag and steering wheel. The only special tool needed would be a steering wheel puller which you can borrow from Autozone. The part is about $120.

I'm not sure if this fix would solve your problem but it is something to consider.
 

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I have a 2001 siverado 1500 5.3, and i have the same problem. I have 2 factory keys and the intermitten non-starts happens with both. I don't think it's the keys. Is there any other way to fix this security light problem? thanks for all the help guys....
 
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