1998 Silverado Passlock Issue ---- ugh

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Hello,
I'm hoping someone may be able to help me on what I think is a passlock issue...

I go to start the truck, and it will start and run for a second or two.. then shutoff... passlock light flashes when the truck shuts off.

Now, I tried to do the 10/30 minute passlock relearn procedure.. Heres what I do.

- I attempt to start
- then leave in the on position for ten minuets
-The instructions say the security light should stay on.

The problem I have is the light will not stay on, so I cannot seem to get it in relearn mode. When I attempt to start, the security light will come on and flash for a few seconds, and then goes off.

Any help would really be appreciated. This truck is super frustrating.
 
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df2x4

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You may be already aware of this, but a good mail order tuner like Black Bear Performance (or any local tuner who uses HPTuners software) can disable the Passlock system entirely in the PCM. This is the route I always recommend to people having Passlock issues in the '98+ trucks. Everything else including the resistor/relearn method is just a way of fooling everything into working. The whole system is a pain anyway. Any real vehicle thieves can work around it quickly, the only thing Passlock seems to do is cause inconvenience to the actual owner.
 

HotWheelsBurban

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Yes that's the best way. I had this problem with my truck last year, and was about ready to shoot it! Many people on this forum have been where you are and that seems to be the only way to fix it. My personal experience was that l would do a relearn process and it worked once or twice and then I'd have to do something else. I talked to a couple of garages in my area and they referred me to a shop that mainly works on LS vehicles, but one of the things they do is computer tuning. It was $250 that I didn't want to spend but it was well worth it. I get in it and it starts first time, every time. Good luck with your truck!
 

Chevy-SS

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This is a VATS issue - Vehicle Anti Theft System.

If you're at all handy, then fix it yourself. I had a '98 K1500 that did exact same thing. I took it around to a few shops, they were perplexed. Dealer wanted to install new wiring harness for HUGE money, LOL. It was ludicrous.

So I went Googling and found this solution (in pic below). You will need an Ohms meter and a soldering iron, plus you will need to find a resistor that matches (within 5%) the ohms reading that you get. I bought the resistor at Radio Shack, but they are now closed. Certainly, you could order resistor online if it came to that. Or you may have an electronics shop nearby that has one.

Anyway, this VATS bypass procedure worked perfectly. After I did it, I never had any more problems at all, and the guy I sold it to never had any issues either. My total cost for fixing was about $2........................ :)

In the pic below, you access the "three small wires" by taking off the cover under the steering wheel.

If you need any additional help, email me at: davefra@hotmail dot com

You must be registered for see images attach


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what year is your truck , there are three different passlock systems, i had this happen to my 98 , and unlike most i like to keep things original as possible so i replaced passlock module with a rebuild from a company out of the mo. area , my passlock says when the light stops flashing turn it off for a period of time then turn it back on for a period of time 3 times, and that worked for me, i dont know how much it cost for a bypass but im thinking unplugging or cutting wires are involved and i hate doing that ( may be wrong on that dont shoot me ). and a reman module is 140.00 with shipping with a lifetime warranty


PASSLOCK Reprogramming Auto Learn

PASSLOCK REPROGRAMMING AUTO LEARN

IMPORTANT: If a new vehicle/powertrain control module (VCM/PCM) is being installed for the first the manufacturing enable bit will be set and the auto learn procedure may not be necessary.

The following procedure allows for anyone to reprogram the EVO/PASSLOCK (TM) module learned data code with any tools, other than the scan tool, when any of the following parts are replaced:

  • The EVO/PASSLOCK (TM) module
  • The PASSLOCK(TM) sensor
  • The VCM/PCM
The EVO/PASSLOCK (TM) module will set the DTC B3031 in the learn mode when entering the reprogramming procedure.

IMPORTANT: Erase the PASSLOCK(TM) related Diagnostic Trouble Codes (DTCs) that are stored in the VCM/PCM. If there are any powertrain related DTCs, record these DTCs then refer Diagnostic System Check.See: Powertrain Management\Computers and Control Systems\Testing and Inspection

The following is the Auto Learn Procedure:

  1. Insure the ignition key is in the ON position.
  2. Clear all EVO/PASSLOCK(TM) module and VCM/PCM DTCs. Record and refer any VCM/PCM DTCs to "Diagnostic System Check". See: Powertrain Management\Computers and Control Systems\Testing and Inspection
  3. Momentarily rotate the ignition key to the CRANK position (Do NOT start the vehicle), then release it to the RUN position (Do NOT key OFF in the process).
  4. Wait 10 minutes . Observe the SECURITY indicator. Refer to the following list for the appropriate responses:
  • If the PASSLOCK(TM) sensor was replaced the SECURITY indicator will flash for the 10 minutes duration.
  • If the EVO/PASSLOCK(TM) module was replaced, the SECURITY indicator will flash for a few seconds and then remain ON for the remainder of the 10 minutes duration.
  • If the VCM/PCM was replaced with a new programmed VCM/PCM and connected to the vehicle for the first time, the vehicle will start and this procedure may not be necessary.
  • If the replacement VCM/PCM was connected to any vehicle at any other time, even momentarily, the SECURITY indicator will flash for a few seconds and then remain ON for the 10 minutes duration.
  1. The SECURITY indicator will transition from flashing to ON briefly to OFF after 10 minutes if remaining in the ignition ON position.
  2. Turn the ignition switch to the OFF position and wait for 10 seconds .
  3. Repeat steps 3-6 two more times. The new security code is ready to be communicated among the PASSLOCK sensor, EVO/PASSLOCK module and VCM/PCM. The new password is learned on the next ignition lock cylinder cycle from OFF to CRANK to ON (start attempt).
 

df2x4

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i dont know how much it cost for a bypass but im thinking unplugging or cutting wires are involved and i hate doing that ( may be wrong on that dont shoot me )

You're wrong, but I won't shoot you. :lol:

Bypassing Passlock in the PCM tune as I described above requires no physical modification to any parts. Anyone with access to HPTuners can do it in about 10min so if you can find someone locally it should be pretty cheap. Most mail order companies will do it as part of their tuning process, which is usually around $300. Some of them may be willing to do just a Passlock disable for cheaper though.

EDIT - The cheap resistor bypass does require modification to wiring, though.
 
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iRIEYEZ

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Waianae, Hi.
I'd also have my suspicion that over time, the resistor hack fails, too, as connections throughout the circuit age and resistance increases. Tuning it out is the permanent fix.

Richard
Can HP tuners tune out vats if the truck is missing passlock module?
 

Pinger

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When PassLock intrudes - ie, starts for 2 seconds then quits - if starting is attempted again - does the process just repeat? If so, will it do this repeatedly until the battery flattens?

Can PassLock intrude on an already running engine - or is it only a timed thing after that initial fire-up? (Ie. within 2 seconds after fire-up/cranking ceases)
(Don't concern yourself with the impossibility of it being able to be started in the first place - I'm asking this for an engine that can be started on an alternative fuel).
 

df2x4

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Can PassLock intrude on an already running engine - or is it only a timed thing after that initial fire-up? (Ie. within 2 seconds after fire-up/cranking ceases)

That I believe I can answer. To the best of my knowledge PassLock cannot intrude on the operation of an already running engine. What makes me say that is there's a specific bypass method which involves switching a signal wire and interrupting the PassLock signal while the vehicle is running, and no mention of the engine dying when you do so.

https://www.gmupfitter.com/files/media/photo/284/Bulletin_20.pdf
 
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