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how to bypass faulty passlock systems

04-28-2007, 07:53 AM
This is only intended to be used if you are having PK2 issues and do not want to pay big bucks for the stealership to do their thing. I assume no responsibilty here. I know for a fact this works 99% of the time and if it doesn't, you can easily revert back to the way it was prior. Please verify that you do indeed have a PK2 failure before trying this method.

1. Locate the PK2 wires. They're tiny 22 gauge wires that run with the bigger 16gauge wires that run the ignition, start, and accessory wires. There will be 3 of them usually yellow(resistance), black or orange black(ground reference wire), and white. The white one you will not use.

2. If the car will start at this time what you'll do is meter the resistance value. To do this you cut the yellow wire in 2 and put one lead from the meter on the end that goes to the igntion switch and the other end to the black or orange/black wire (do not cut the black wire). Put the car in reverse (without trying to start it) Once you do that crank the key like you are trying to start it. You'll notice that the meter will be changing values at this time. Once it settles down, you'll see the value needed.

3. Get resistor(s) that come as close as possible to the value you had gotten. If it's something like 1495ohms but you can only get 1490 or 1500, get the slightly higher number. Install your resistor(s) by attaching one end to the OTHER end of the yellow wire that goes towards the car's dash and the other end of the resistor(s) to the black reference wire. Once you do that, try and start it. If it doesn't work, try running a new ground wire to the black or black/orange wire. There has been a few cases where that wire was the culpret but it's far and few between.

3a. If you couldn't get close to the resistor value needed or if the car still won't start do this. Turn the key to make the ignition come on, don't crank it. Leave it like that for 10 minutes. After 10 minutes, do it again. If the security lights flashes, turn it off and then start it. If it still doesn't flash, turn it off and then back on for yet another 10 minutes.

You should be good to go now:naughty:

Moderators, please make this a sticky!!!!

05-19-2007, 02:20 PM
ponchonutty, based on what they said on the last page found on the link below, I've been trying to figure out the practical aspect of wiring a resistor in. They explained the theory but it didn't help so much for the real world of finding the right wires to solder the resistor into. Your method worked great, thanks.

If any of you are wondering about whether you should do this method or the "putting a switch in the wire" trick, I'll let you know what my experiences were.

First of all, both methods do work. I ran my car for a few days with the wire cut while I was trying to figure out how to finish the job with the resistors. Secondly, in my opinion cutting the wire is way easier. It's kinda annoying having the light on the dash, but other than that it's by far a simpler fix.

You may have read about having to re-enable the system if you lose battery power. This is also true. During those few days where I was driving with the wire cut, I really wanted to just leave it that way. I didn't want a battery failure to cause me to have to tear the dash apart and reconnect the two wires. So to test it while it was still torn apart, I disconnected the battery for a half hour and then tried to start it again. No luck. Disconnecting the battery does indeed reset everything and the only way to restart the car again was to just reconnect the wires and hope that the ignition cylinder was able to put the right signal out at least one more time.

So the solution is a switch so you don't have to tear the dash apart again? Right. Except for two things. One is the annoying security light all the time. The more severe is what would happen if you don't lose battery power for a year. You've been driving every day and the ignition cylinder components, while being bypassed, have still been being used every day and have been getting in worse and worse condition.

You find that you have to replace your battery one day so you do. You start your car and crud, the security light starts flashing again. Oh well, flip the trusty switch, wait 10 minutes and try again. Hmmm. It's flashing again. Well, it just must have been one more isolated case of the system not working. Give it another 10 minutes.

Six hours and 36 tries later you've still got a flashing security light and the only solution is to go buy a 300 dollar ignition cylinder so that you can finally get a good signal to the cars computer again before you can even bypass the system again.

I figured I wanted a permanent solution so that's why I went after the resistor method. So far I've been very happy.

My car was giving me problems three or four times a week before I put the resistors in there. Sometimes it would do it twice in a row. When it did actually start the security light would usually come on halfway through the trip I was making. Since I installed the resistor I have not seen the security light even once, either while starting or enroute. Thanks again for the great info ponchonutty!:cheers:

05-20-2007, 06:20 PM
Hey, thanks for the praise. I'm so glad you figured it out through my posts on how to get this to work. Very nice right too I might add!

05-29-2007, 11:40 AM
i haved a 1998 malipoo.. and the passlock has screwed up for the 4 time in 2 years. i have read about bypassing it with cutting the yellow wire and installing a ressistor to the same r value. but what i havent read, and the question i would realyy like to know is. my car will not start at all. just for a second then the light flashes again, can i bypass the passlock with out getting any signal to BCM. or does the passlock have to be opperating at the time of bypassing it.:banghead:

05-29-2007, 12:31 PM
For this trick I am about 90% sure that it has to be working enough for you to read the correct resistance that the ignition unit sends out. If it's failed beyond all hope I believe you must buy a new lock. I've read about some tool that GM has that you can stick your key in and find out what resistance value the ignition cylinder would spit out with that key and then you could try that resistance but I'm not sure if that's fact or fiction.

Basically I'm saying that you'll probably have to buy a new ignition cylinder but when ponchonutty sees this he might have some better advice for you.

05-29-2007, 08:44 PM
Well, having the system working at the time of bypassing it certainly helps but isn't needed as long as the defunct part IS the ignition switch. You can still go through the process I lined out and see if you get a different reading for the PK2 value. If you don't, it should be doable. Just go ahead and get a resistance value in there then go through the "new ignition switch code learn" procedure and you should be good to go.

06-05-2007, 10:07 AM
the anti theft light is not blinking like it did last time. i assumed it was since it was acting like it did the last few times.could this mean it is somethingelse, i tried to reprogram it but to no avail. the door buzzer makes a funny noise.
i checked to r value and got a value of 4.5. the readings on my meter go froom 2000k, 200k 20k, 200. i took the reading on the 20k. is that the right settting to use.

06-07-2007, 09:38 PM
Yes. So you need a 4500 ohm or 4.5 ohm resistor or how ever many resistors to get that value.

06-13-2007, 09:13 PM
Are the yellow and black wires coming out of the ignition lock cylinder? I suspect they are. To get to them do you have to remove the cylinder or can you do the bypass w/ the cylinder in place?

06-14-2007, 11:00 AM
I tried the resistor method w/o great success (so far). I measured the resistance w/ my multimeter set at 2000 and I ended up w/ reading of 1815. I went to radio shack and the closest resistor they had was a 2.2K or 2200. I wired it up as mentioned above. The car starts but the theft light is on. I suspect the resistor is too far above the 1815 level and I have the equivalent right now of just cutting the yellow wire. What do I do if there is no resistor close to my resistance reading? :banghead: I took pictures as I did this to post them but can't figure out how to get them on w/ my posting. Not my day I guess.

06-14-2007, 03:26 PM
Ahh sweet success. Guess it may be my day after all. After a little internet research I found you can add resistors in series to get the level you need. connected a 1/2 watt 1500 ohm (or 1.5K) and a 1/2 watt 330 ohm resistor w/ a small barrel connector to get above the 1815 ohm level I needed. You can view resistors at to see what values they have and to know what you need before heading off to Radio Shack.

I cut the yellow wire and attached a fully insulated male connector to the ignition side and a fully insulated female connector to the dash end of the yellow wire. I connected the resistors together as above. Then on one end I placed a fully insulated male connector and attached this to the female connector on the dash side of the yellow wire. I was not succuessful in removing insulation from the black wire w/o breaking the wire but it worked out well for the wiring in the end. I connected a fully insulated female connector to the ignition end of the black wire. Then I connected a crimp pin connector to the dash end of the black wire and the other end of the resistor. Both pins slide in nicely into the female connector. Car started fine and the theft light did not come on.

For curiosity I called the dealer. The ignition lock cylinder was $187, recoding for my key was $49 and labor was $131 for a total estimate of $388. I spent $14.64 at Radio Shack. It only cost me this much because I needed the connectors. The resistors were $0.99 for a pack of 5. I borrwed the multimeter to measuree resistance which saved my some $$ but this would have been a good reason to buy one.

I thought about trying the cleaning method but chose to do the bypass instead since I already had it exposed and the cleaning method was not as guaranteed in my mind. Also, a can of electrical cleaner at Radio Shack was $11.

I was worried my radio was not going to work since I disconnected it before I read not to. Figured the anti theft device in the radio would disable the radio. Luckily it did not and the radio worked find after reconnection. Even held the stations programmed in. Ironic that while fixing the faulty anti theft system in the ignition that the anti theft measure I was expecting to work in the radio didn't work either.

For 1997 Malibu owners, get to the wires by removing the trim panel around the radio and the radio. (Disconnect the radio at your own risk.) You can see the ignition cylinder to the left. The wires for the passlock system are together inside some black sticky tape. There is enough wire to pull them into the space where the radio was to work.

Thanks ponchonutty for the guideance above. I am not mechanically inclined and if I can do this anyone who can read, differentiate color and cut a wire can do it. It took me around 2 hours total w/ 2 Radio Shack trips and several trips back to this web page. Now that I know what I am doing I think I could do it again in about 30 minutes.

06-15-2007, 03:02 PM
Yep glad it worked good for you. Also, great follow-up post!!!

For those of you that have an older Gm vehicle with the PK1 system (like a '98 Olds I worked on) this method will not work. The reason is that the PK1 system is more picky about what goes on when it's "reading" the code. It does everything the PK2 system does but also has a bulb check wire. I haven't figured out how to time things right and get it bypassed. Once I do, I'll post it but for now, the above information is soley for the PK2 system.

09-18-2007, 04:01 PM
Hello everyone! I own a 98 malibu and have had theft system troubles since about day three. I purchased the car in '03. I started having trouble with the no start condition and the flashing theft system light not long after I installed a crime stopper remote starting system. Eventually, the car refused to start with the key, and for about a year the remote was the only way the start the vehicle.

I am friends with a fellow who worked at a Gm dealership as a mechanic, and so I asked him about it. He took the car and had a new tumbler installed, and it worked great... for about 4 months.

Then one day it totally refused to start at all. So, in my fury, I completely removed the remote start system and finally got it to start somehow. After that it worked OK for a while.

Now in the last 2 months it has started the crappy no start stuff again. So after researching this forum, I decided to try the resistor fix that ponchonutty has described. I read all about cutting the yellow wire and faulting the system out, but I wanted to not have to mess with hoping that when I desconnect battery power, that the ignition switch would still function properly one more time. I am in to car audio competition, so unhooking battery power is somewhat a common practice.

Out to the car I went, with my multi-tester in hand. When testing for resistance, I came up with 3.7 k/ohms. Then it was off to Radioshack, where I purchased a package of five 3.9 k/ohm resistors for $.99. Wired up the resistor, and used the relearn method method to accomidate the new resistor. To the key I went and tried to start it and...
... Holy Crap It Lives. Restarted the car several times and each time it started!!! No theft light flashing and no steady theft light while running.

Thanks to Ponchonutty's information, a 20 cent resistor has made me not hate my car so much. I will only repost if I run into any more trouble, but I am confident this simple proccess has saved the day. The 45 minutes it took to do this install doesn't even to compare to the amount of time has been wasted watchin that stupid theft system light flash.

Thanks a million Poncho!!!!!!

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