Passlock problems? Anyone know of an easy fix or work-around?

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by HiLineMan, Nov 16, 2007.

  1. flamecop

    flamecop New Member

    I had this problem and it did not get completely cured until the passlock module in the dash was replaced by the I recall it was quite reasonable, +/- $200 out the door.
  2. zubbiez

    zubbiez Epic Member 5+ Years 500 Posts

    the wife had this happen in my truck the other day I wasnt sure if it was the passock or not, she just called me and said my truck woudnt run, so I went done to where she had Broken down checked the sprak and fuel pump they where fine. messed with it for about and hour got pissed off and just left the truck there and went home. about five hours later me and a friend went to tow it home with his truck. tried the key and it was running. I was pissed got home and the wife mentioned oh way I slipped when I whent to put the key in so I think its the passlock. put my diablo predator on the obII and it actuall had a passlock code. Ill have to remmder not to touch the key for ten minutes the next time she touches my truck.
  3. colorado_kool-aid

    colorado_kool-aid New Member

    you can buy a passlock bypass module from Kragen-O'reilly $20.
  4. HiLineMan

    HiLineMan New Member

    Thanks for the info, but I am having trouble finding this online. I searched for "passlock bypass" and "passlock" and got zip. I tried "module" and got lots of things, but none related. Any ideas?

    As an update: the Sub seems to be having the problem more frequently, and the "on-off three times" work-around has not worked for my DW on two different occaisions. What did work was the "turn to the on position and wait till the security light goes off" work-around did work, but that has taken 30-40 minutes. Not very practical in most situations.
  5. bflo99burb

    bflo99burb New Member

    Another possible WA


    I have been having the same issues with my burb -- also on camping trips. I tried something this past weekend that seemed to work -- I pulled the fuse for the security (on mine it was #21) and re-inserted it. After I did this, it started right up -- I am assuming somehow this reset the PassLock system.

  6. HiLineMan

    HiLineMan New Member

    Well .... here we are, 4 years since my last post, and guess what? We are still dealing with this problem. About 1.5 years ago I had the resistor bypass installed. It worked great for 6 mos then started acting up again. My mechanic found a GM service bulliten that he said involved going through the wiring & connections of the Passlock II system, cleaning contacts and soldering some connections. He did all those things last Nov, it worked fine for 6 mos, now we are back to the same problem, crank but no start. He found a relearn proceedure that takes 30 mins, for a number of times it worked.

    Then on 7/10 it wouldn't work on my key (K#2). On 7/10 it had started fine with K#2 about 730AM but when it came time to start it to hook up the trailer (about 830AM), it wouldn't start, same old thing, crank no start. I went thru the re-learn 3 times with K#2 and never got it to start. My DW went thru the re-learn once with her key (K#1) and it started right up. We have used K#1 ever since. The way it seems to be working now (note: this is working theory #237 (at least)) is as long as we continue to use only one key (K#1), it works fine. If we start it with another key (say K#2), it will work fine once or twice, then it gets “confused” and suddenly thinks every key we try is not a good one, until you go through the 30 min re-learn process with K#1 and then all is ok. Since it is working ok with K#1, and my mechanic is very busy right now, I won't mess with it for the time being. My mechanic is trying to find out which module has the "memory" that the re-learn proceedure fixes. He thinks it is either the BCM (Body Control Module) or the PTM (Power Train Module). As soon as we figure out which one, we will probably try replacing it. -Dave
  7. oklagirl71

    oklagirl71 New Member

    So I know this is an old post, but looks like it started again...basically with my 1998 Gm truck (passlock2). I've gone through about the same. Started with starter, then to fuel pump finally security light came on then changed ignition. Security light is on and can drive but getting locked out (fuel pump is shut off) and having to do the 30 minute reset every couple of days. The aforementioned fixes through a mechanic (as I'm female and hate to get dirty but I'm one hell of reader of forums working in the IT business I understand schematic pretty well). Was all set to have an alarm dude cut wires and put a resistor in, but then I saw somewhere if it gets cold (Colorado does) this problem may pop back up. Low and behold I saw on another GM site someone said THE ONLY RELIABLE WAY TO BYPASS VATS (which ever one you have) is to reprogram the PCM (Powertrain Control Module). Two key things in all my reading I've found in the last year. If you locks aren't intermittently locking by themselves, other lights aren't flashing, windshield wipers don't suddenly come on, other weird problems- more than likely your BCM is ok. If it takes the 30 minute cycle and relearns the code so you can drive it til it locks again then "probably" it isn't your PCM. From what you describe it sound like the actual passlock sensor, BUT in theory could also be bad wires/connectors somewhere along the way or even random voltage spikes can cause it (Head spinning and pulling hair it's high dollars anyway you go other than replacing ignition and it is sensors in keys and/or tumbler)....similar to as me except I don't have old keyes cause they replaced ignition already. I looked for a high performance shop- a diagnostic tuner. Happens to be one in my town called BoostCreep. Slapped his laptop computer on with HP tuner (different programs do different cars just because one shop says no I can't doesn't mean others can't, they just don't have your vehicles software) Disabled the VATS system (cause HP tuner calls it a VAT) reprogrammed the PCM and VIOLA no more problems for $30.00 (security light can stay on while driving- one small side effect). GM certified shops and dealers will not do this, most mechanics can't do it. You have to find the guys that are doing the high performance aftermarket things with their cars....follow the line of the little bumblebee annoying import cars in town and they will lead you to one :) The only reason I am posting here is because there is so MUCH information on cutting the wires, putting a resistor on and so little information on reprogramming the PCM to reliably bypass the vehicle anti theft systems.....Good luck!!!

    - - - Updated - - -

    -PS when they reprogram the PCM they should save a schematic of your original factory settings, this way if you ever want to go back to original (just enable the VAT again) you can
    Last edited: Jul 26, 2013
  8. HiLineMan

    HiLineMan New Member

    Thanks so much "oklagirl71". I am going to forward this info to my mechanic and see if he can do this, or knows someone who can. The problem with intermittent problems is that you are never really sure any fix has worked until the problem is gone for 2 years. :shocked: Thanks again, Dave
  9. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    What type of resistor did they use? Did they just use the module with the dip switches? I have installed a few of those on vehicles with remote starters and they are terrible. Sometimes they work, then the weather changes and they do not. Some of the good remote start system companies sell a self learning "automatic" resistor module for the passlok 2 system. I have had luck with them working for a long time. I would contact a local alarm/remote starter install company and talk with them. They may be able to take care of your issue for under $50
  10. HiLineMan

    HiLineMan New Member

    I believe they measured the resistance then tried to duplicate that resistance with a couple of fixed resistors in parallel. Then they went thru the re-learn procedure with the key, it worked fine for six months, then acted up. Our latest work around is to always use one remote and one key. Lock and unlock the Sub with the remote, then get in and start it. My wife messed up last Saturday, while on a camping trip. She forgot to lock/unlock with the remote, since the Sub was already unlocked, she just got in and tried to start it. It wouldn't start. I did the re-learn procedure and it has worked fine ever since.

    I have sent the info from the previous two replies to my mechanic. I am waiting for him to look over that info and see what we want to do. THanks for all the help! -Dave

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