View Full Version : A fix for Passlock Problems

06-15-2007, 06:25 PM
Like most GM owners, I've had my share of problems with the Passlock system, both on my Alero and my older Cutlass. Many people have the dealer "fix" it, only to have the same problems return later. My dealer says there is no permanent fix, but after some research, I've found one.

GM Truck Group UI Bulletin #26 describes a method to disable the Passlock system to allow for the installation of a remote starter.The procedure can easily be modified to work for a GM car. Here is a link:

I also have found an article that explains how Passlock works, which will help in your troubleshooting. You should read this before attempting to fix a Passlock problem. Go here:

The procedure calls for installing a switch in the Passlock circuit that allows you to disable it while the engine is running. The car will interpret this as a failure of the Passlock system, not a theft attempt, and will go into a "fail-enable" mode.The Security light will come on, and stay on, but Passlock will not be active. The car will start with any key that turns the ignition cylinder.

The security light cannot be turned off (but read to the end) while the car is in "fail-enable" mode. If you go to a shop and get all your OBDII codes read, you will have a Passlock failure code. If that code gets cleared, then Passlock will be active again, and you will have to hope you can get the car started one more time, to enable you to flip the switch you installed, and cause it to go into "fail-enable" mode again. DO NOT let anyone clear all your codes after doing this procedure! The GM procedure says that disconnecting the battery will clear the code, but I had it disconnected for 1/2 hour and it didn't cause any problems.

There is another method of bypassing the Passlock system. If you feel comfortable doing a little soldering, it's not very hard, and only takes about an hour (less time than I've spent sitting watching the security light flash!). Go here for the procedure:
Be patient, the page takes a little time to load.

I just did that today, and it seems to work pretty well so far.

Following the GM bulletin will result in having the security light on all the time. I didn't like that,so I removed the instrument cluster by removing the two screws in the black plastic cover around the gauges. That piece will then pull out. Disconnect the trip odometer button, and set the piece aside.

The cluster comes out by removing the four 7MM screws at the corners. It may look like it will not fit out the hole in the dash, but it will. Unplug the connector, and take the cluster to the bench.

Remove the back of the cluster by prying up all the tabs on the back(not the ones by the gauges). You will have to pull (gently!) the circuit board for the PRNDL lights off a little post to remove it all the way.

The main circuit board can be removed by prying it off its electrical connections. Find the LED for the security light (mine was marked D14). You can break it off with pliers, or unsolder it like I did.

Assemble in reverse order, remembering to put the PRNDL circuit board back on it's post. Now, when you start the car, the security light will never come on.Edited by: Iflylow

09-22-2007, 08:09 PM
Just to let everyone know, I used this fix to bypass the Passlock on my Daughters car. Worked like a champ.

08-20-2008, 06:19 PM
is this method the same for passlock 1 systems I have a 97 achieva


08-20-2008, 08:36 PM
I don''t know if the adding resistors method will work for the Passlock one system or not, I''m really not familiar with that one. However, read the article in the original post, it does talk about Passlock 1, so maybe you can figure it out.

do you have a chip in your key?

08-21-2008, 04:08 AM
nope no chip.

I cut the wire today and put a toggle switch in to try it out.. if it works great.. if not ill try the resistor. and if that doesnt work.. solder the stuff back together

08-21-2008, 10:51 AM
I would recommend the resistor, because the toggle switch will only work until you disconnect the battery or your codes get cleared by someone. Then you will have to hope the key will work one more time.

The resistor is a permanent fix, regardless of how worn out your ignition cylinder becomes. You may have to solder two resistors in series to get the correct resistance. Radio Shack has them cheap, I think I paid $1 for ten. You don''t have to get the resistance exact, within 100 ohms worked for me.

10-21-2008, 11:00 AM
I have a 2001 impala that is having the same passlock problem. Could someone please email me the fix to Thanks

10-31-2008, 05:22 AM
2002 Chevy Express G1500 van, 305cid, auto. would not start, mechanic said new key cylinder and key neededand i did install them. still would not start due to PassLock programming.mechanic instructed to leave key in RUN position for at least 20 minutes and i did so. van started and continued to start without fail for 2 weeks. now van will not start and is exact same symptoms. cannot figure out how brand new key cylinder and brand new VIN matched key is failing again after that fixed the problem before. corrosion in wires? engine computer failure? **please e-mail fix.** have read literally hundreds of stories about PassLock failures that strand people, cost lots of money. any chance GM will recall this crap? genuinely thinking about replacing drivetrain with manual tranny and carburetor intake, etc. NO MORE ELECTRONICS! Thank you for any help!

314802@comcast.netEdited by: AMSOIL314802

11-01-2008, 12:30 PM
Was the security light on during the failed start attempts? If not, you do not have a Passlock problem. The Passlock wiring is very sensitive, like you said, if there is some corrosion or a loose connection, you will have intermittent problems.

Usually a BCM (Body control module) computer failure will show other symptoms in addition to a "no start" condition.

I''ll send the service bulletin.

11-15-2008, 09:24 PM
I have a 99 Chev S10 I owned since 1999 when I bought it with 6800 miles on it. At that time I put in a Kenwood CD AM/FM CD unit. It now has 88,600 miles on it. About a month ago I, the Security light, battery light, ABS light, seat belt light would come on occasionally while I was driving. The water temp gauge goes to zero, and the fuel gauge indicates empty, and the gear indicator disappears ( the letters are there). Sometimes this goes out by itself while I''m still driving. Usually the Security light goes out and all the gauges resume normal operation on restart. I should also say that for some time I have been having to give the shift lever a litlle extra nudge to get it into Park or the ignition would not turn off power fully ( the battery light would stay light when I shut the truck off).

Please send me the Group VI #26 Bulletin to: ''''

11-16-2008, 12:10 AM
Email sent. Your problems do not sound like they are caused by Passlock, however. Sounds more like an ignition switch problem.

11-17-2008, 12:49 PM
Was the security light on during the failed start attempts? If not, you do not have a Passlock problem. The Passlock wiring is very sensitive, like you said, if there is some corrosion or a loose connection, you will have intermittent problems.

Usually a BCM (Body control module) computer failure will show other symptoms in addition to a "no start" condition.

I''''ll send the service bulletin.

Thank you for your prompt reply and help!

New problem was fuel pump, which mechanic said is about right considering number of miles on van: around 100,000 miles.

Replaced fuel pump. No problems for 2 weeks AGAIN.

ThenEnginelight lit up! :(

Code Scan revealed Thermostat/ECT sensor fail and Fuel Pump gas sensor fail. Research revealed cold motor due to thermostat failure can cause Fuel Pumpgas sensor failure. Replaced ECT sensor and thermostat which solved codes.

No problems since! Knock on wood! Thanks again!

02-26-2009, 05:44 PM
can anyone tell me what the relearn method is? And also how do I tell if I have a passlock 1 or a passlock 2 system?

02-27-2009, 04:47 PM
Reply sent.

Passlock I and II both work the same way, so the resistor method works for both.

The Relearn method is described in the article linked on the original post.

03-19-2009, 05:08 PM
OOK has anyone heard of this with the passlock system, I bought the car used and the owner said it needed a starter, it would jsut spin without engaging. I got a new starter from ebay, put it in ran fine drove car to work stopped 5 times shut off car each time started back up each time. Went to leave at end of day would turn over, sputter, backfire then starter would only spin ot engage. I towed car home took out starter put jumer cable on it worked spi and engaged, checked old starter it worked to. Put back in car only spins, both of them spin. I tried the waiting thing 5 tries security light went out still spins. Any help on this? Please email me link to disable it.

03-19-2009, 09:16 PM
No need to create two posts about the same problem. BTW, I moved your other post from the New Members section to the Alero section. Welcome!

I don't think you have a Passlock problem. Passlock only prevents the PCM from allowing fuel to the engine. The starter will still turn it over regardless.

03-27-2009, 02:16 AM
Please email me this,thanks,Dan.

04-29-2009, 07:24 PM
Hello, I hope you or someone else can help me with my '95 Aurora.
Since a few weeks I have the problem that my car will not start anymore when it is too humid or too cold ... or whenever it will not start. I get the message on the BC "Clean Key - wait 3 min" ... but the car starts later (minutes, hours, days ....) with that key without a problem. So I guess that the contacts for the resistor pellet are worn out. Thinking of that, I decided to bridge the contacts like it is described for the passlock problem.
I measured the key, found a matching resistor and now ... I'm standing there looking for the right cables to cut.
Does anyone know or can tell me, which color they have for my car, from which connector at the steering column they come (the big almost square one or the flat shaped one), which gauge they have (22 or 16 ?) etc ... every possible information that could help me, to find the right cables. Please, I love this car and want to drive it ;)
I looked already here, but that is not really helping me ...

04-30-2009, 12:20 PM
That sounds like a VATS problem, for sure. I would recommend trying a brand new key with the correct resistor pellet before cutting wires. It is probable that the contacts on the key and ignition cylinder are both worn out, and a new key will be wide enough to make contact. Any GM dealership will be able to make you a new key, but I think they cost about $15, and you will need to show them the title to the car or they won't do it.

I had a 95 Cutlass that had the same problem, but mine was fixed by cleaning the key. I also wet the pellet, and inserted and removed it several times to clean the contacts inside the ignition switch.

I think your wires will be 22 gauge, and probably yellow or yellow/black. I will email you a pdf of the 95 cutlass start circuit which may help. Send me a private message with your email address. I was not able to find a wiring diagram for the Aurora.

VATS sends a constant 5 volt signal through the circuit, even when the car is off. I would check each pin of the connectors for 5 volts (between the pin and ground). There may be more than one with 5 volts, but that will narrow down your choices. Once you have found 5 volts, insert the key in the ignition, and measure resistance of that wire on the other side of the connector. When you find one that is close to the resistance of the pellet in the key, thats the wire you want. You will solder the resistors you bought between that wire (probably yellow) and ground (probably black).

Hope this helps.

04-30-2009, 05:29 PM
Ok, thank you so far, that helps a lot :) Especially the 5V thing. I've read a lot on the net, so I was sure that it can only be the passlock/VATS system and therefore for me the safest way to make my car work again was trying to bridge that stupid thing.
I have a little bit experience in cars (I learned to be mechanic back in Germany and learnt on a French brand, which also had/has a lot of electronical issues), so I just wanted to try this ... but then I was a little bit overwhelmed by the amount of cables behind the steering and I just don't want to cut the wrong wire/s ... another thing is that one of the previous owners installed an alarm system and therefore the cables do not really look like they were originally.
From what I understood, when I cut the right cable while the key is in the lock on ignition and the security light is off, the lsystem should go in fail mode and the light should go back on? Is it possible that the cable is light yellow? That's the smallest I've found so far, but now that I know, I will try to measure the 5V before cutting the cable.
Thank you again for your help, and I will send you a private message :)

05-01-2009, 06:53 PM
Yes, when the car is running and the wire is cut, Passlock decides that there has been a Passlock system failure, not a theft attempt. The security light may come on (mine did) but the car will not shut off, and Passlock will disable itself. Then, any key that will turn the ignition cylinder will start the car. If you get your codes read, it should show a Passlock failure code. Once that code is cleared, Passlock will be reset, and again look for the correct resistance.
VATS may work a little differently, I am not very familiar with its specific logic, but I would guess it's about the same.

05-06-2009, 08:52 PM
Ok, thanks for your help, I finally had the time to fix it yesterday evening. I found the cables comming from the ignition lock, followed them and saw that they ended in big something of insulating tape, where someone else one day installed an additional alarm system. He made a really bad job, because when I just pulled a little bit on the wires, they came out of the tape very easily, and blank ... so, after just measuring the resistance it was clear, that these were the cables I needed, switched on ignition and got the good old "clean key - wait 3 min". Ignition off, resistor in between the blank cables (freed from tape) and ignition on: the security light went off instantly, and I could start putting everything back again in the right position.
Now I don't have to worry about worn out contacts, keys, passlock failures ... thanks again, you helped me a lot :)
Btw. sorry for the incorrect mail ... I just saw it now, that I forgot a dot ...

10-05-2009, 07:32 PM
Passlock, fuel system, trac off.....oh my!

Okay I am loving the information on here and I WANT to believe it, but I am stuck on one thing:

1999 olds alero V6 2 door. While driving it dies like it was unplugged. MIGHT sputter once - I'll catch my rps's dip..then a min or two later it cuts off. I sit and try to start it until it starts. Sometimes 3 min, sometimes 10 minutes. NO flashing SECURITY light. Sometimes I get in it and it doesnt start. No flashing security light. I turn ignition to on - HEAR my fuel pump humming, then try to crank it and it cranks rough like its getting no fuel. After a few min it starts and runs like a champ (thats why this is frustrating - when it runs, it runs great). I'm afraid to drive it now since it is unpredictable. I have been going 25 MPH and 40 MPH and it just shuts off - no power, no nothing. If it is the Passlock I am amazed GM would not recall this unsafe thing - dying while driving - but alot of the posts talk about flashing security lights..mine stays on with the check engine light and various others.

There are GREAT posts on here with the same symptoms, but a lot of stories of "and I dropped 300 bucks on X and it worked for a week then the problem came back..blah..blah..." I am broke as a joke, so I cant waste money replacing working parts. Help?

11-11-2009, 07:21 AM
Hi everybody!
Im new in this forum and, coming from Austria, hope that my english is good enough. I am driving a Olds Alero, first registered in August 1999 here in Europe. I hope that there are no differences between US-cars and exported cars as far as the passlock/passkey/theftlock system is concerned.
My car has about 140k kilometers (~88k miles), and the "Security"-problem has just began to show up.
I am very grateful for the solution outlined in this thread since I just talked to the local Chevy (over here they sold the Alero under the Chevy brand) dealer. The outlook was something around 700 EURO (about 1k US-Dollar), which seemed way to expensive to me.
Now, Id like to try the resistor solution, but just to make sure that itll work for my car I need some help with the anti-theft systems, which I tend to confuse:
My cars VIN is:
1G1NL52E3XC00097, Type 1NL69 ABAA
I am nut sure if my car has Passkey I, II, Passlock (I, II?). I remember seeing "Theftlock" somewhere in the manual, so Im a bit confused.

Could anybody please help me so I can go to work before my car shuts down on the Autobahn?

Thank you!


11-12-2009, 11:10 PM
Theftlock is a system that prevents the radio for working if it is installed in another car. It is not related to Passlock II, which is what your Alero has.

The resistor method should work for your car. Be aware that if you cannot find a resistor with the correct resistance, you can link several together and add their resistances until you reach the correct resistance.

Your English is better than that of many people who were born speaking it:)

Let us know how the bypass works for you.

12-12-2009, 03:37 PM
I had a local alarm shop wire in a resistor. Basically bypassing the passlock. No problems since. They charged me 60.00 I waited while they did the job about 20 mins. I had to call about 4 shops. Most knew of the problem but the one knew the resistor bypass.

03-23-2010, 10:17 PM
I experienced this for awhile. Sometimes it would happen 6 or 7 times back to back. Sitting at a corner store with the security light flashing for over an hour in the hot and humid Florida summer is not fun. One day while under the hood I was messing around and noticed that the positive battery terminal bolt had screwed up threads and was not getting a good connection. I replaced the bolt with a new one and since then I have not had 1 issue with the passlock system.

04-10-2010, 02:00 AM
After doing alot of reasearch on this problem like the hundreds that I have found all over the web, I have to learned there is no fix for this problem, I have also came to learn that this is a manufactures defect in the Anti-theft system that apparently GM and Oldsmobile does not want to take responsiblity for. So I came a across a site that was very interesting, and for all that has posted to this forum should look at. Its call the NHTSA, which is the National Highway Traffic Saftey Administration website, here is where we all need to send out compliants in and they will review them and this is a they determine if a car or parts of a car are subject to a recall...I contacted them after I filed my compliant and was told that there has to be a signifiant amount of people with this same problem for them to do something once a complaint is filed, and they WILL get something done..please pass this along to anyone you know that has an Oldsmobile or any car that is having this problem.....we need a fix for our cars. Here is the actual link to file the compaint

04-13-2010, 01:51 PM
Sorry, this is not going to be a recall, as it is not safety related. Passlock has been a problem on GM cars for more than 10 years, with many hundreds of thousands of vehicles affected. There is in fact a fix, see the first post.

05-07-2010, 09:55 PM
Posts on 95 Cutlass Passkey 2 problem moved to Cutlass section.

05-17-2010, 03:50 PM
Well the only reason there is not goin to be a recall is that they can only recall if there have been complaints made, and that is what the website is for. I was told that when I called them. So if nobody calls then, nothing will get done, and as for this not being a saftey issue, it is, passlock does infact link itself to other things that can go wrong with the electrical units in your car. Is has been linked to malfunctions in the air bag systems and also the horn systems as well. Just an FYI to anyone else thats having this problem.

05-17-2010, 05:06 PM
There have been tens of thousands of complaints about Passlock over the past 10 years. There will not be a recall, sorry, I wish they would, but it isn't going to happen.

Passlock does not link to airbags and other safety related equipment. It is only an antitheft system. Sometimes ignition switch problems are misdiagnosed as a Passlock problem, and the ignition switch does link to just about every other system in the car, including airbags. A bad ignition switch can be very hard to figure out due to the large variety of electrical gremlins it can cause.

Ronny Resistor
05-28-2011, 06:41 PM
This not starting thing is confusing, I read in this forum that if the Passkey fails you will still have the motor turning over, however no fuel is getting to the engine. So what is the cause of no engine turning over. I can hear some relays (assuming the fuel pump clicking). I measured the voltage during starting and found no voltage drop (weak battery). My starting relay is getting 12 Vdc. (removed the relay and measured the relay post to ground). But no starter solonoid clicking. I read somewhere that all you have to do is remove the battery and the system will be allowed to be reset, however I am not sure if the problem lies with me waiting 10 minutes or disconnecting the battery. As for the + terminal post being corroded I checked and it is ok. I read that there is a little control circuit that will bypass the system, however I am not convinced that this would be the way to go. I can however believe that the contact in the key-hole is worn out.
Today I gave my son the spare keys (never used) and hope that the problem goes away. By reading all the Blogs with regards to this Passkey problem it has been going on for quite some time, but today is 2011 and I would expected more positive feedback from all GM manufactured vehicles on this WEB site. As for safety concerns i would be more worried about my 19 year old trying to go through an intersection and having the car stall. Again shame on the manufacturer. Someone must have been injured or worse killed already due to the system shutting off the fuel.

Enough said

Anyone that cares to answer me I would appreciate you contact me direct in or on this site. PS I am an Electronic Engineer so technical doesn't bother me.

05-29-2011, 06:26 PM
First, the 2001 Impala has Passlock, not Passkey. The two systems are different and fail in different ways.
Second, Passlock was installed and works differently in the Alero than in the Impala. Aleros will crank with a Passlock failure, but the fuel injectors are disabled. Impalas will not crank or have fuel. You should have a flashing "Security" in the message center of your Impala if Passlock is preventing a start in the Impala.

Passlock will not cause a stall after the car has started. If the system detects a Passlock failure while the car is running, it goes into "fail-enable" mode, triggers the "Security" light on steady, and stops monitoring the key. Any key that will turn the cylinder will start the car in that mode.
A Passlock failure when the car is not running is interpreted as a theft attempt and the injectors (Alero) or starter and injectors (Impala) are disabled.

I would not expect a voltage drop during start if the starter is not turning over. Without that the load is not very big at all. If you don't have a "Security" message, I would swap the starter relay with another one, you may just have a bad relay. I can't remember if there are any more relays under the hood with the same part number, you may have to get a new or used one to try.

Read the links I referenced in the first post in this thread. The resistor bypass method works in the Impala as well but I think the wire colors are different, so you will have to check a diagram for that. For further troubleshooting, I would strongly recommend you search here:
This is one of the best Impala sites around, many of us on the site there have dealt with this issue before.

08-21-2011, 10:07 AM
The problem has been getting steadily worse for the past year, we started using the spare key a couple months ago which allowed it to run but the security light stayed on continuously. Now it has started thinking we are stealing it again.
Okay, I've read every post up to this point and visited the links provided in the first post and I am still puzzled as to the exact procedure.
I have done the resistor fix on my sons 92' camaro a few years ago, getting the resistance was easy as touching the chip contacts with my meter, the alero has no such chip in the key....... how does it determine resistance? is the key just a straight contact with the resistor being inside the lock cylinder?
Like I said I've been through everything here and either from fatigue or frustration have overlooked something.
Thanks in advance for any help.

08-22-2011, 08:42 AM
First I want to apologize for not posting the results after asking in this forum. The solution described by iflylow using the resistors worked perfectly in my (since kaputt) 1999 Alero 3.4.
I can only recommend to re-read the article mentioned/linked by iflylow in his initial post as it really contains every information necessary.
I wasnt careful the first time and thus used a resistor with a wrong Ohm-setting, but once I read the measurement in the correct Ohm-range it worked immediately.
I hope youll succeed!


08-27-2011, 01:13 PM
Okay, I really need some help here. I've gone back through this thread again but did not find anything specific enough to proceed. I have a 2004 alero which would be a passlock III system... correct? The links in the first post show passkey I and passlock II but not III. I have read elsewhere that this system cannot be bypassed with the resistor method, is this true? and do I just need to resolve myself to buying a new ignition/key switch and trying to get it to relearn/ accept the new key?
In either circumstance is there anyone with knowledge of how the #%*! you get to it? I have removed the lower panels and from what I see there are screws holding it to the dash but they come in from the front and I don't see how to remove them.

08-27-2011, 11:46 PM
First, let me say I am not familiar with III, the procedures posted work with II, however they may also work with III.

The resistance is built into the switch, you are correct there is no resistor in the key. That is one of the primary differences between Passkey and Passlock. When you clip the yellow wire, you can then measure the resistance between one end of it and ground. Click the link for the exact end to use, I don't remember right now.

When I installed the resistors, I had to approach the ignition sylinder from the pax side. I removed the shifter knob, then pried up the whole plastic piece around the shifter, it just snapped out. Then I pried out the trim around the radio. I don't recall if I had to pull the radio or not, it's been 4 years ago now. I think you will have to pull it, but maybe not disconnect it. You will then be able see the wire bundle coming from the back of the ignition switch, and find the Passlock wires you need for the bypass. The whole process of gaining access to the wires is not as hard as it sounds, and maybe takes 15 minutes.
Good luck, let me know how it goes or if you get stuck in the process!:)

08-28-2011, 05:29 PM
Thanks for the reply, I had considered radio removal to allow access but wasn't sure if the procedure would work on a III system so I did not proceed.
It will be a few days before I can attempt the bypass and let you know the results, in the mean time my wife and I are swapping vehicles till this is resolved.
Many thanks,

02-07-2012, 04:01 PM
Hello everyone. I was having the same problem on my car. After doing the key restart for several months it finally got to where it would never start.

The dealer wanted to charge me $1000 just for the parts to fix it and to be honest I would rather set it on fire then give them another dime.

I found that you can do the wire cut method but this will only provide you a temporary fix. Eventually the other parts of the system will fail and you will be back to square one. The average lifespan of your passlock parts is less than 7 years. Why buy another BCM so it can fail again?

I got lucky because I found this site They sell a bypass that takes passlock out of the equation forever. No more failing parts. They also sell a manual that will instruct you to build your own bypass if you are handy like that. I wasn't. They really saved me because there is no way I could afford the new parts.

07-20-2012, 02:16 PM
Hi I have a 2002 alero the car started great when I got it. Now the security comes on at times and won't start but will turn over and starts when the batt is almost out of power and fires right up or I got to turn it over till it dies and get a boost. I have cleaned the tumbler oiled it and now got the tumbler kit with the magnet and wires. Put it in and it stared all day yeasterday till today. The thing to replace from what I know it the black box in the dash witch is $80 used. So far I have put out almost 400 in 3 months. Will this be my last thing to fix or could it be more things cause it never seams to end.

12-29-2012, 02:14 AM
I would recommend the resistor, because the toggle switch will only work until you disconnect the battery or your codes get cleared by someone. Then you will have to hope the key will work one more time.