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Possible Passlock Security system Weekly Problem

Discussion in 'Chevy C/K Truck Forum' started by j.myles.gardner, Sep 26, 2011.

  1. j.myles.gardner

    j.myles.gardner New Member

    Hey guys,
    I’m new to the forums here, but I am looking for help with my beloved truck. I have a 1998 Chevy K1500 Z71 with 169XXX miles. About a year ago my key began to wear out, so I had the ignition lock cylinder replaced. Not immediately but soon after I began to have problems. It began to intimately not start. The symptoms were the fuel system would cut off immediately after starting, and the security light would began to 5 times and then shut off. The truck would not start for a short period of time, but it seemed to start after i let it set for 30min. I was told it was the pass lock system and Chevy mechanics have told me to replace the pass lock sensor in the ignition cylinder, the PCM (pass lock control module), and have the system re-flashed. None of these items worked at fixing the problem. I tried to do a lot of research on this, but it seems that none of their methods have corrected the issue. I am looking to see if anyone here would have some insight to why the truck is killing the fuel pump and locking the ecu for a period of time.
    Thanks for your time and interest,
    J. Myles Gardner
  2. j.myles.gardner

    j.myles.gardner New Member


    If you need me to provide any more info please let me know, I have been to multiple gm dealers and 2 master mechanics have been unable to help with this problem. I would love to keep this truck and get it fixed instead of selling it.
  3. ShadowRejects

    ShadowRejects Rockstar 100 Posts

    Welcome to the fourm! and this is a strange issue ive never heard of. you might have to have the ecu/computer reset to factory standards if you can have a professional do that. other than that i have no idea. sorry man
  4. j.myles.gardner

    j.myles.gardner New Member

    Thanks Shadow, I have had the ECU re-flased by the local dealer, but problem still persisted. I have been putting a bit of money into this truck, and I want this problem to stop stranding me for hours at a time, god knows where.

    Tomorrow I am having a new security/remote start installed on the truck, I have discussed this with the tech and have decided that I am going to have a passlock bypass done, hopefully this will work.
  5. TRPLXL2

    TRPLXL2 Epic Member 5+ Years 1000 Posts Platinum Contributor

    The bypass will work!!

    I did one on an engine swap on a 97' firebird, the VATS or passlock would tell the car to give no fuel and the car wouldn't start for three minutes and the security light would flash. I didn't have to reflash the computer or anything, I looked up the wiring diagram for the steering column and found it. There was two white 22ga wires under the steering colum, that had orange shrink wrap on them. I snipped the two wires, and on the side coming from the ECM I wired in a resistor that matched the pellet value of the key. It cost me about $0.2 to do myself, my honest opinion is the dealer scammed you out of a good buck for the "reflashing" The theftlock works off the BCM anyways, NOT the PCM(ECM)
  6. j.myles.gardner

    j.myles.gardner New Member

    Cool, that is awesome to hear. I have read its a simple job after you find the ohms resistance coming from the passlock, and splice a resistor in. I guess I will soon see if it works.

  7. j.myles.gardner

    j.myles.gardner New Member

    Just as an update: The bypass seems to be working, the resistor need was a 2.62kOhms. I will see over the next few weeks if it was 100% successful.
  8. TRPLXL2

    TRPLXL2 Epic Member 5+ Years 1000 Posts Platinum Contributor

    I am so glad to hear that, I just wish you would have found out sooner but we all learn some how. It took me 3 seperate attemtps to get mine to bypass correctly, because there is only a 5% tolerance up or down with that. Mine was like 0.519, which made it a combination of 2 resistors which is hard to solder under the dash LOL! Thanks for updating!
  9. j.myles.gardner

    j.myles.gardner New Member

    Crap, well I hope this is within the tolerance range, the closes the tech could get was a 2.7kOhms. Either way Ill let everyone here on this thread know.
    Thanks for the help guys.
  10. j.myles.gardner

    j.myles.gardner New Member

    TRPLXL2, how long did it take for you to find out that you didnt have the correct resistor in there? was it with in a week or so?

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