Finally a cheap passlock fix! - Page 3 - Chevrolet Forum - Chevy Enthusiasts Forums
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Finally a cheap passlock fix!

mobileinstaller's Avatar
CF Beginner

Join Date: Mar 2010
Posts: 23
Jackson, mi

March 3rd, 2010, 11:53 PM   #21  
Jtea hear is the problem

ok first off changing the ignition switch and tumblers will do absolutely nothing sorry if you have already done this. there are three main components to the passlock II system the passlock sensor, the BCM, and the Ecm and of course the wiring in between. Odds are if this keeps happening and there is no other problems such as door locks freaking out trunk release just goin off then it's not the bcm if you do the relearn feature and it works the it is also not the Ecm. so you are left with the 3 wires that run from the bcm to the passlock sensor.odds are the passlock sensor is bad. now there are two solutions either go to the dealer and have the sensor replaced or bypass the system for good. any respectable mobile electonics installer should be able to do this no problem it takes me about 20 mins and i personally charge 40 dollars to do so hope this helps also if you are mechanically inclined in electronics i can send a diagram on how to bypass it yourself hope this all helps

Tegrish's Avatar
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Join Date: Mar 2010
Posts: 1

March 14th, 2010, 10:10 PM   #22  
How to bypass the passlock system

Hey there MobileInstaller! I have had a problem with my 1997 cavalier. I just bought it last week. I had to put a new starter, alternator, battery, and ignition switch in it and I had it running for 1 day. It ran great! The next day however, I went to start the car and it ran for about 2 seconds. I have tried everything I have read in the forums to get in running. No luck as of yet. I have not noticed any theft light coming on though but i dont have any dash lights anyway. lol Anyways I was wondering if you could help me out with a wiring diagram to bypass it myself. I would love to be able to bring it somewhere to get it worked on but I live 3 hours from the nearest big town so I think I am on my own here. Thanks for the help!

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Join Date: Jun 2006
Posts: 61

April 12th, 2010, 1:40 PM   #23  
UPDATE: Did the below fix almost a year. Started acting up again about a month ago. Security light always coming, have to wait 10 minutes for passlock reset (almost every day). Had the below fix done again about a thousand miles ago. Works absolutely perfect again. No securit light, starts every time. My mechanic showed me the contacts, and they were badly burned again. He took a dremel with a brush and cleaned them like brand new. I think the problem is GM using inferior metals. Also had to fix my service traction control by cleaning the contacts by the wheels, more than once. Hope this helps someone else, sure has helped me.

Posted By: jondoe28 Had this done a couple of weeks ago. Hasn't acted up once, security hasn't come on at
all either. Hired our tractor mechanic to do it. Said 2 contacts were burnt on key switch.
Used sand paper to clean them, and good to go. Cut and pasted from another site:

I just fixed my 2002 impala security light issue. It cost me 2 hours, no money. Here is how the system works. The passlock sensor and the ignition switch are in series. When you turn your key you generate a low current read by the body control module. If the current generated is out of range the BCM won't recognize the signal and your car won't start for 10 min. There could be different reasons why the signal is out of range. On most of the cases the ignition switch contacts are burned out, and this will cause a voltage drop on the contact so the signal getting to the BCM is going to be lower than usual so it will be out of range. Take your ignition switch out (if you don't know how send me your e-mail (believe me I'm not looking for e-mail addresses I just need to scan the instructions, since I have them only printed out) and I'll send you detailed instructions for free. Once the switch is out remove the cover on the back of the switch (it is clipped on, all you need is a flat head screwdriver). Once the cover is removed you should see 5 fairly big electric contacts. I bet at least one or two are burned out. Clean them with fine sand paper until their surface is clean and flat and make sure the steel springs pressing the contacts together are tight and are pushing the contacts firmly. If not, using pliers bend them to get good contacts. Reinstall the switch and your car should start every time. If the contacts are really bad you might have to change the ignition switch.
I know dealers want to change every part on the car so please do not let them change the passlock sensor. The passlock sensor is a hall sensor and there is no reason for the sensor to go bad.

rags's Avatar
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Join Date: Apr 2010
Posts: 4

April 30th, 2010, 7:49 AM   #24  
passlock 2

man im new on this board and i hope someone can shed some light,i have a 2002 monte carlo that worked fine for the last few years,i didnt drive it for awhile ,i had to charge the battery and i was going to start the car and nothing, no click no turn over ,the light flashes i can hear some clicking when i turn the key, i have tried all the internet fixes 10 minute wait,take the ignition apart ect, ive been out of work so i cant take it to a dealer can someone point me to the correct way to diagnose and fix this problem ,thanks rags

MDTAHOE's Avatar
Super Moderator
Professional Mechanic

Join Date: Nov 2008
Posts: 2,955
Bowie, MD

April 30th, 2010, 10:37 PM   #25  
If your car does not crank then the factory security system is not the problem. you need to start checking at the starter and work your way back. You need to see if the little wire gets power while you attempt to start.

rags's Avatar
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Join Date: Apr 2010
Posts: 4

May 3rd, 2010, 9:56 AM   #26  
passlock 2

i checked for voltage at the batt im good i jumped the starter and it turns over but gets no gas from the injectors,the security light comes on and blinks all i need is to find the correct procedure to find what part is bad the ignition was replaced 2 years ago so if you have some info it would be great i need to get this running so i can look for work ,thanks rags

Last edited by rags; May 3rd, 2010 at 2:30 PM.
herewego's Avatar
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Join Date: May 2010
Posts: 1

May 6th, 2010, 9:49 AM   #27  
Passlock sensor was replaced now same problem

I replaced the passlock sensor a few weeks ago and yesterday the car wouldn't start. Acted the exact same as it did when the dealer told me it was a bad passlock sensor. Now they are telling me it is my after market remote start that has beenon there since a week after I bought the car in 2005. The passlock sensor replacement was very costly but I finally did it after almost a year of them saying that was the problem. The said the new problem does have a code showing up so it is not the passlock sensor now. I don't agree as I don't see how the symptom can be the same for two different problems. Any help would be great.


chevyp2p's Avatar
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Join Date: Jul 2009
Posts: 6

May 6th, 2010, 2:54 PM   #28  
1999 Suburban Won't start

Hell guys I have a problem similar to the one you are describing. The truck starts up but then dies after a second or so, however I don't get any flashing security light.

I have replaced the passlock module and did a relearn as recommended in alldata, but that did not solve the problem.

Could be this a passlock problem or should i start looking somewhere else in the truck?

Thank You.

jimmyk's Avatar
CF Beginner

Join Date: Jun 2010
Posts: 2

June 24th, 2010, 9:02 PM   #29  
Cleaning contacts

I just took my ignition switch apart and looked at the contacts, two were discolored, so I shined them up with some fine steel wool and I haven't had a starting problem since, thanks for posting this info.

2001 Impala LS 70,000 miles

jondoe28's Avatar
CF Junior Member

Join Date: Jun 2006
Posts: 61

June 27th, 2010, 4:17 PM   #30  
I'm glad it helped you too. I was pulling my hair out with this problem until i found the fix.
Mine still works perfect.

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