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

Finally a cheap passlock fix!


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  #1  
Old  April 14th, 2009, 4:35 PM
  • CF Junior Member
    Join Date: Jun 2006
    Posts: 61
Finally a cheap passlock fix!

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.

  #2  
Old  April 14th, 2009, 8:07 PM
  • CF Monarch
    Join Date: Jul 2007
    Posts: 6,151
    Princeton, NC, USA
Excellent. Glad you got it fixed!

  #3  
Old  April 15th, 2009, 6:10 PM
  • Super Moderator
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sorry to say, but the passlock, and ignition switch are 2 totally different systems. They are not wired in series and have nothing to do with each other
The wires for the passlock go straight to the BCM without any detours. The BCM sends a 5v reference signal to the passlock sensor, goes through the resistor in the sensor, and goes back to the BCM. If the voltage sent back to the BCM does not match what it has stored in its memory, then you get passlocked out.

Your probelm was probably with the ignition switch the entire time.

And passlock sensors DO go bad regardless of what someone told you

  #4  
Old  April 20th, 2009, 8:52 AM
  • CF Junior Member
    Join Date: Jun 2006
    Posts: 61
I'm happy things work normal now. I've been using my remote starter for 2years because
i kept getting passlocked out, and having the security on when i drive probably 75% of the time. What you're saying is the key switch has nothing to do with the passlock system at all?

  #5  
Old  April 20th, 2009, 6:56 PM
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The key Cylinder has everything to do with it....the ignition switch does not.

  #6  
Old  April 23rd, 2009, 9:03 PM
So, should I give it a try?

Shawnvw, Should I give the whole sandpaper thing a try? My 99 Suburban is so bad I have to sit for hours sometimes, waiting for it to run. Today was 5 hours and two jumpstarts. I was told to leave the key in the on position for 20 minutes before trying to start it. That worked for a few years, but recently I'm passlocked out several times per week. usually it takes 4 or more tries of 20 minutes before it will run again. I am desperate because I do not have the money to take it to the dealer. I did get a new key cut from the dealer, though, with no change in passlock behavior.

I'm a girl and have only pulled one key cylinder in my life, on a Grand Am. I do my own brakes, etc. and am somewhat mechanical. But I don't want to start something that is unrelated and won't work. I'm okay with a "possibly". Is it possible this will help me?

Thanks!


Last edited by Tired of Passlock; April 23rd, 2009 at 9:11 PM.
  #7  
Old  April 24th, 2009, 4:19 PM
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Passlock only takes 10mins to relearn itself. If you are taking hours, i'll bet that either the sensor is no longer sending the resistance to the bcm, or you have some wiring issues.

Are you sure that the vehicle is going into passlock? Does the security light flash if you turn the key on(engine off)?

  #8  
Old  April 25th, 2009, 7:36 AM
Thanks for answering Shawn. The security light always flashes when I turn the key into the on position. Sometimes when the car finally starts the security light will stay lit for the whole trip, even for several hours.

What do you think should be my best plan of attack?

  #9  
Old  April 26th, 2009, 9:09 AM
  • Super Moderator
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It could be a few different things wrong with it...the passlock sensor in the Ignition cylinder, the BCM, or the wiring in between.

Without a scanner\tech2, it can be kind of difficult to diagnose. Probably the problem is in the passlock sensor, but I cannot say for sure without seeing the vehicle

  #10  
Old  April 26th, 2009, 6:34 PM
  • CF Junior Member
    Join Date: Apr 2009
    Posts: 52
    Vero Beach FL
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.


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