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Discussion Starter #1
Has anyone deemed an absolute bypass fix of the stupid Passlock system? I would like to actually take the car on a vacation without worrying about the dang security light coming on and stranding the family in the middle of no where or some gangland. PLEASE enlighten me. I have read several different options. I don't want to just start guessing and changing. I just want to bypass the thing. It's a base model 3.4 and I'm not worried about having a security system.
 

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8th Gen Antagonist
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Do the base models have passlock? I haven't seen any evidence of it on any of ours. Have you checked the connections to the BCM?
 

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My security light comes on everytime i start the car. if it chooses to lock you out it's normally 10 minutes until it resets (in most cases). Overall gm flaw in the design but they would never admit it.
 

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One trick I learned is to turn the key to the "on" position and wait 3 seconds then start the car. From what I have read this normally takes care of the system doing the 10 minute lockout.
 

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IIRC you can use your headunit(if you still have the stock one installed) and that will alow you to access your security settings. ie passlock, trucklock, sercurity chimes and what not. With the car off and the key in the "on" position push and hold dispaly whilethe headunit is powered off. Wait 15 sec and a options menu will pop up. Cycle thru the options and you should see the settings I was talking about. I'm not 100% if im right, its been a while since I played with those settings, but its worth a look none the less.
 

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Discussion Starter #7
One trick I learned is to turn the key to the "on" position and wait 3 seconds then start the car. From what I have read this normally takes care of the system doing the 10 minute lockout.
Funny you mentioned this. One week ago we went into a restaurant, came out and absolutely nothing. After several tries, even jump start, I was so pissed...My wife sat down and just turned the ignition on and sat there for a bit, then turned it over and started. It also was about 5 seconds until we saw the security come on. Now I do it all the time, wait for a few seconds until I see the security light flash back and forth with the battery. Crazy....I don't trust this car farther than I can throw it.

Please GM, do the right thing and recall this system to have it bypassed forever!
 

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I hear you man, I have the same fuchin' problem with my Impala. I hate the anti-theft system. It does more harm than good. You see I'm old fashioned and rather hunt down and shoot the thief than using some obnoxious alarm system that will just make him want to bypass so he can steal the car. What I had done in the past, was take out ignition switch then reconnect it. It helped for about 5 months then the same "fuchin" problem came back again. I want this dumb, ain't worth my two cents, anti-theft system out of the Impala. I hate it, it does nothing but deny access to the rightful owner.
 

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I found this last night in my computer. I do not remember where I got it from, and sadly I forgot I had even had it. I hope this helps.


GM Passlock–Diagnosing and Fixing GM Anti-theft related no-starts

The GM Passlock system is fairly simple, especially when compared to other makes. However, if yours is goofing up, you won’t think it’s so simple.
Here’s how it works: When you first turn the key, the PCM provides power to the fuel pump, injectors, and ignition system. You can crank and start the engine. However, there’s a magnet built into the lock cylinder. As you rotate the key, the magnet passes over a Hall Effect sensor—a sensor that detects the presence of a magnetic force. The magnet produces a unique voltage when it passes over the sensor. The sensor sends this voltage signal to the Body Control Module where it is compared to a stored value. If the sent voltage doesn’t match the stored value, the PCM shuts down the fuel injectors for a minimum of 10 minutes and, well, you’re pretty screwed at that point. If you try to start the car again, you will see a blinking Security light. That’s your sign that the Passlock system has shut you down.
What goes wrong: GM vehicles experience a very high failure rate in the lock cylinder and lock housing mechanisms. Fortunately, they’re fairly inexpensive and easy to replace.
Testing the Passlock sytem: Remove the plastic cover shrouds from the steering column near the lock cylinder. Inside you will see the Passkey module surrounding the lock cylinder. It will have 3 wires coming out of it. Turn the key to the ON position and use a DIGITAL multimeter (Do NOT use an analog meter) to backprobe the probe the black and white wires. If you see 12 volts on the white wire and 0 volts on the black wire, you can proceed to the test for the Passkey module. If you do not see those voltage values, you have a wiring problem between the connector and the BCM.
Next, connect your voltmeter to the yellow wire. It should read 5 volts. Keep the probe connected and turn the key to the off position and back to the start position. The Passlock Data Voltage has a potential of 10 different values, ranging from .86 to 4.28 volts. The voltage should drop to a voltage level between those values and stay within .02 volts of the initial reading for at least one minute. Repeat the test several times—you must receive the same voltage for each test. If you do not, replace the lock cylinder and the Passkey housing.
To remove the lock cylinder, first disconnect the negative battery cable and allow the airbag to power down for 5-10 minutes. Slide the Passkey module off the cylinder housing. Insert the key and turn the lock cylinder to the start position. Place a 1/16” allen wrench into the hole on top of the lock module to release the steering column lock cylinder set pin. Then turn the lock cylinder to the RUN position and pull the lock cylinder out. Reverse the procedure to install.
After you replace the cylinder and Passkey module, you will have to conduct a relearn procedure for the BCM to learn the new voltage value. Here’s the procedure: Lock doors and unlock. Clear codes. Turn key and bump starter, leave on for 10 minutes. After a few minutes the dash light will go out. At that point, turn the key to the off position for 90 seconds to 3 minutes. Repeat this procedure 3 times for a total of 30 minutes and on the 4th try the car will start.
© 2007 Rick Muscoplat
Posted by Rick on Monday, May 12, 2008 at 9:11 pm
 

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8th Gen Antagonist
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One thing, 7th gens have the ignition in the dash. You have to remove the face of the dash, screws are on either end, above the instrument panel, and I can't remember but I think there were a couple below the column as well. The rest just snaps into place.
 

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Discussion Starter #11
Whoaa! This magnetic thing is the first I've heard of this. I've been reading about cleaning contacts and resistor value's. Someone please pipe in again and share a link to what works as a bypass for the 2004 Impala Passlock.

Has anyone petitioned against GM for a recall or bypass fix for this system? If there is one, I'll sign right away.

It's very upsetting not to drive this car on a family vacation in fear of the 'Security' monster taking a bite. I borrowed a 98 Olds mini-van with 150k miles, a head gasket patch seal, and old Serpentine that I trusted more than an '04 Impala...now that's sad.
 

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I'm struggling with the same problem and posted the same question a few days ago. Thank you all for sharing your knowledge.

Jim
 

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that thing called passlock is a pain in the but, my impala used to show the security light while driving but after stoping the car and turning it up again it always started, that used to happen like 1 or 2 times per month
 

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Discussion Starter #14
just locked me out twice in two weeks, probably a 5% failure rate...not good. I know have the dash torn apart. Is the access best from the ashtray side I removed? Now what? Does it pull through that ashtray access and should I remove the negative terminal from the battery?
 

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well i did the test on my pass lock wires on my wifes impala trying to hook up a remote start and i was getting 12v on all three wires when the key was in the ON position but my BCM is good no don't know what to think.
 

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Mr. Handy
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The passlock fault is in the ignition switch. This is a very common failure/defect. Replace the ignition switch and you might as well replace the cylinder as they can junk up with dirt and cause problems. It requires removing the dash which others have mentioned. It also requires getting the cylinder keyed (assembled in correct order) by either a locksmith, auto shop, or dealer.

P.s. Get this fixed asap! A failing ignition switch can cause major damage to the electrical system.
 

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Do the base models have passlock? I haven't seen any evidence of it on any of ours. Have you checked the connections to the BCM?
I know this a older thread but I would like to know if all models have passlock? I have a 04 with the 3.4. There is no security light when you turn the key or alarm setting on the factory stereo. Thanks in advance.
 

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Mr. Handy
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You can't shut passlock off but, you can bypass it
 

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8th Gen Antagonist
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I later determined that all trim levels are equipped with it as well.
 
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