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"Tamper" mode? Starts/stalls repeatedly, 10 minutes later it's fine


Chevy-SS
12-23-2004, 11:08 AM
Anyone have experience diagnosing "tamper" mode issues with the VATS (vehicle anti-theft system)? I have a 98 Silverado which will run fine for about a month, then when I go to start it, it will run for a second, then die. It will do this until I just let it sit for about 10 minutes, then it will start and run fine for another month. It's driving me crazy. :screwy:

I had a remote starter installed about a year ago and I suspected that might be part of the problem. I took it back to the installer, but he swears that the remote starter is completely bypassed when I use the key switch. He is saying that the problem lies somewhere in the VATS. It could be the resistor wire or the processor or the computer??? :confused:

I notice my "security" light coming on every once in a while while I'm driving, so I am pretty sure my problems are in the VATS components somewhere. Anyone have any recommendations to help locate the problem?

MadMac56
12-23-2004, 11:12 AM
Had that problem with my wife's malibu...pretty common problem...got worse & worse till BINGO out $400 for a new puter

Chevy-SS
12-23-2004, 11:16 AM
MadMac, did you do the job yourself or did the dealer do it? If you did it yourself, was it difficult?

MadMac56
12-23-2004, 11:20 AM
I shoulda...wasn't covered by the extended warranty...but the old lady handled it while I was at work...not sure how much was part & how much was labor...but I'd be willing to bet the part was at least half

banshee350twincyl
12-23-2004, 06:20 PM
Im having the same problems as you but the only difference is that i dont have to wait 10 minutes, i try to crank it back right away and it cranks the 2nd or 3rd time, think it could still be the VATS. My trucks a 98 also .

Jerry243
01-06-2005, 12:20 PM
I've got a 99 Silverado and had a very reputable business install a remote starter. Sometimes it works, sometimes it does not and when it does not, the security light flashes and I was told I need to put the key in the "ON" position for 10 minutes to bypass security issue, then start with key. I'm very dissapointed and am seriously looking at having the thing removed; fortunately, I have a lifetime warranty on parts and labor.

Thunderbolt
01-06-2005, 03:56 PM
I have a buddy with the same problem and from what I have been told these trucks don't like after market remote starts. His causes the security system to activate. Does it do it even if you never use the remote starter ?? His seems to work if he never uses the remote starter, But if he tries to start it with the remote it dies and won't even start with the key for ten minutes. I don't know what brand his is, But he was standing outside talking to his neighbor one day and the neghbor sarted his car with his remote and at the same time it started my buddies truck !! Thats real promissing when someone elses remote starts your truck.

Chevy-SS
01-06-2005, 04:15 PM
OK, my truck (98 Silverado) pissed me off today. :banghead: It did the same "tamper mode" thing. I tried to use my remote start and it wouldn't start, I waited five or ten minutes, and then it started right up.

So today, I got ambitious and did the permanent bypass on the security wire. I found some instructions on the web. I cut the yellow wire, then measured the cranking ohms resistance at 577. Then off to Radio Shack, where they had 560 ohm resistors +/- 5%. I bought a pack of five for 99 cents. I measured the resistors to find the best one. Closest I could get (to 577) was 554 ohms, so I soldered that one onto the yellow wire (processer end) and into the orange/brown wire.

The instructions said I needed to be within 1% to 2% on the ohms. I was more like 4% off the 577, but the truck fired right up with no problem. :wink: I will be curious to see if the problem is now solved. I will post results after a week or two and let everyone know if this fix worked.

I'm no expert at this, but I've always suspected the remote start, especially as the resistor security wire goes through it via a relay. So now, I have completely eliminated the remote starter from the resistor security wire.

If this doesn't work, then I am gonna assume I need a new computer.

ponchonutty
01-07-2005, 07:17 PM
OK, my truck (98 Silverado) pissed me off today. :banghead: It did the same "tamper mode" thing. I tried to use my remote start and it wouldn't start, I waited five or ten minutes, and then it started right up.

So today, I got ambitious and did the permanent bypass on the security wire. I found some instructions on the web. I cut the yellow wire, then measured the cranking ohms resistance at 577. Then off to Radio Shack, where they had 560 ohm resistors +/- 5%. I bought a pack of five for 99 cents. I measured the resistors to find the best one. Closest I could get (to 577) was 554 ohms, so I soldered that one onto the yellow wire (processer end) and into the orange/brown wire.

The instructions said I needed to be within 1% to 2% on the ohms. I was more like 4% off the 577, but the truck fired right up with no problem. :wink: I will be curious to see if the problem is now solved. I will post results after a week or two and let everyone know if this fix worked.

I'm no expert at this, but I've always suspected the remote start, especially as the resistor security wire goes through it via a relay. So now, I have completely eliminated the remote starter from the resistor security wire.

If this doesn't work, then I am gonna assume I need a new computer.
I can't say without looking at these vehicles but will tell you that GM has a high failure rate even without remote starts installed.

On the total bypass trick, I have found it better to be about 2% and have the resistance value a little higher versus being a little lower. For some reason when the temperature changes, you truck probably won't work because you are 4% AND lower than what it needs.

Chevy-SS
01-08-2005, 12:23 PM
Ponchonutty, thanks for the feedback. Exactly what parts are you referring to when you say "high failure rate"? Computer? VATS processor? Security wiring harness?

So far, so good with this mod. The truck is working perfectly and the "security" light is staying off. I will take your advice though, and look around for a resistor that more closely matches the 577 ohms.

ponchonutty
01-09-2005, 09:03 PM
Ponchonutty, thanks for the feedback. Exactly what parts are you referring to when you say "high failure rate"? Computer? VATS processor? Security wiring harness?

So far, so good with this mod. The truck is working perfectly and the "security" light is staying off. I will take your advice though, and look around for a resistor that more closely matches the 577 ohms.

With the VATS systems it is usually the tiny little wires that go to the cyl. lock. They usually shortout from the cyl. being turned all the time to start the car.

With the Passkey systems, not really sure. All that I have ever seen GM do is COMPLETELY change the decoder ring and harness. When I have spoken to the techs, they didn't sound as if they really knew what the cause was either.

Cadillakin'98
01-10-2005, 12:06 AM
So this is a common problem on all '98 full size (GM)trucks? Just wondering 'cause I haven't experienced this yet and hopefully won't but if I do it's nice to have this heads up on how to solve the problem

Chevy-SS
01-10-2005, 08:48 AM
With the VATS systems it is usually the tiny little wires that go to the cyl. lock. They usually shortout from the cyl. being turned all the time to start the car.

With the Passkey systems, not really sure. All that I have ever seen GM do is COMPLETELY change the decoder ring and harness. When I have spoken to the techs, they didn't sound as if they really knew what the cause was either.
Well, if you are correct about the techs not knowing what the problem is, then shame on GM for producing this un-needed complexity.

I have now bypassed those tiny little wires that go to the cylinder lock, so hopefully the problem is solved. Still working perfectly. Plus, I went to see a buddy of mine who works with electronics and he built me a 576 ohm resistor using three in series. So I will install my new resistor which is almost exactly the measured cranking resistance.

I'll keep everyone posted, but right now it's looking like I got this problem beat. :smokin:

Thanks

ponchonutty
01-11-2005, 07:07 PM
So this is a common problem on all '98 full size (GM)trucks? Just wondering 'cause I haven't experienced this yet and hopefully won't but if I do it's nice to have this heads up on how to solve the problem
Well, you can't get a tech to actually admit it :icon16: The ones that I talked to stated they never "dug into it" trying to find the fault. They just simply replaced the system.

It seems that the VATS system is the worse. I had it fail on my '89 Firebird. I average about 4 cars a year that I permenately bypass. As for the (Passkey)PK1,2,and 3 systems, I have yet to bypass one. I have had a few cars that would remote start but not with the keys. Later, the dealer ended replacing the system. I'm with you on this one. Got the PK2 system on my '01 Silverado and so far so good.

Tall
01-11-2005, 07:39 PM
Where did you guys have your remote starts installed? They make an aftermarket Security By Pass for these vehicles. It runs about 60 bucks, depending on what alarm you have the price does differ. As far as I know, with the by pass…there is no issue.

What it does, is tricks the security system into thinking their is a key in the ignition...

Chevy-SS
01-11-2005, 08:24 PM
Where did you guys have your remote starts installed? They make an aftermarket Security By Pass for these vehicles. It runs about 60 bucks, depending on what alarm you have the price does differ. As far as I know, with the by pass…there is no issue.

What it does, is tricks the security system into thinking their is a key in the ignition...

Yeah, I saw those things, but why bother? I'd just as soon do the permanent bypass for pennies and then not worry about it anymore. If a crook wants to steal my vehicle, he'll get it regardless of how many anti-theft devices are on it.

ponchonutty
01-11-2005, 08:51 PM
Where did you guys have your remote starts installed? They make an aftermarket Security By Pass for these vehicles. It runs about 60 bucks, depending on what alarm you have the price does differ. As far as I know, with the by pass…there is no issue.

What it does, is tricks the security system into thinking their is a key in the ignition...
I know, I sell remote starters. The problem is that the bypasses won't work in this matter. You have to trigger them in order to get them to send the "signal". You can't just constantly have the bypass being triggered. That's not how they work.

For instance, my DEI #555L bypass for Passlock1 and 2, it is setup to "read" the code each time you start it with the key.

steve in alaska
01-16-2005, 04:12 PM
Where did you guys have your remote starts installed? They make an aftermarket Security By Pass for these vehicles. It runs about 60 bucks, depending on what alarm you have the price does differ. As far as I know, with the by pass…there is no issue.

What it does, is tricks the security system into thinking their is a key in the ignition...

I installed a Bulldog remote with a 791 security bypass module on my 2002 GMC Sierra..When it would get down to about 10 degrees above, and I tried to remote start it, it would just crank, and not start. Then my security light would come on, and even the key wouldn't start it for about 10 minutes. I guessed I had a faulty bypass module, and apparently I was right. After swapping to a new one, the security light stayed off. Bear in mind, now one of the ignition modules has gone south on me, (a year later, after replacing the security module) but I'm just gonna upgrade my remote starter. I've put over 20 of these things in, and although it's not rocket science, they ARE time consuming!
The homemade resistor bypass is interesting!

ponchonutty
01-16-2005, 07:00 PM
I installed a Bulldog remote with a 791 security bypass module on my 2002 GMC Sierra..When it would get down to about 10 degrees above, and I tried to remote start it, it would just crank, and not start. Then my security light would come on, and even the key wouldn't start it for about 10 minutes. I guessed I had a faulty bypass module, and apparently I was right. After swapping to a new one, the security light stayed off. Bear in mind, now one of the ignition modules has gone south on me, (a year later, after replacing the security module) but I'm just gonna upgrade my remote starter. I've put over 20 of these things in, and although it's not rocket science, they ARE time consuming!
The homemade resistor bypass is interesting!
Yeah, I hate those Bulldog systems. The company is based here in Ohio not too far from my shop but I just can't stand them. I did 2 of their systems earlier this week and neither one worked right!

Chevy-SS
02-02-2005, 08:21 PM
Just a follow-up. I did my home-made resistor bypass (as noted earlier in this thread) almost a month ago now. It has been working PERFECTLY since then. I have not had one problem with intermittent starting. Also, the security light does not ever come on now, except for the normal few seconds after starting.

I solved this problem for ninety-nine cents!

:smokin:

Cadillakin'98
02-03-2005, 12:24 AM
Bitchin'

RODDNTEX
11-15-2005, 08:26 AM
I HAVE BEEN IN MOBILE ELECTRONICS SINCE 1982,AND THIS GM VATS/PASSLOCK IS A JOKE.WORST DESIGN EVER.
I HAVE A 2000 TAHOE THAT I HAVE A REMOTE START ON AND IT WORKS PERFECTLY,THE PROBLEM IVE HAD IS USING THE KEY,SOMETIMES IT WILL START SOMETIMES NOT.SOME OF MY BEST FRIENDS WORK FOR GM DEALERSHIPS AND HAVE TOLD ME HORROR STORIES OF THESE SYSTEMS OVER THE PAST DECADE.ONE SAYS THEORETICALLY BYPASSING THE SIGNAL WIRE SHOULDNT WORK, THE COMPUTER REFERENCES VOLTAGE AND THE RESISTANCE SIGNAL?.I HAVE HAD THE GM QUICK FIX DONE AND THE WHOLE TRANSMITTER REPLACED AND STILL HAVE INTERMITTENT STARTING ISSUES,I JUST PERMANTLY BYPASSED MINE WITH A HARD RESISTOR (AND A TOGGLE SWITCH TO BYPASS MY BYPASS-IN CASE) SO WE WILL SEE HOW IT PANS OUT,ANYMORE WORD AND I WILL PASS IT ON.... :evillol:

Chevy-SS
11-15-2005, 08:35 AM
......I JUST PERMANTLY BYPASSED MINE WITH A HARD RESISTOR ..........

Hey, let us know if it works out for you. I have never had one problem since I did the permanent bypass trick.

Now, quit yellin' with the all caps............


:smokin:

jdeller
03-21-2008, 08:22 AM
anyone know about this thread? I know its old but my truck just did this this am.

Chevy-SS
03-21-2008, 09:42 AM
anyone know about this thread? I know its old but my truck just did this this am.


I'm still here, lol. Haven't left in 2 years. It was getting kinda boring here. :grinyes:

What symptoms r u having?

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ponchonutty
03-21-2008, 08:30 PM
Yep. I'm still around. Search my name and you'll find 100's of threads on it so read up.

woodbite
03-25-2008, 05:39 PM
Chevy-ss. Thank your fix with the resistor is just what I'm looking for. You said, you just installed the resitor with no other parts. No relays or anthing else? My friends 98 chevy p/u is doing the same thing. Crank then cut right off. His fault though, I think. He beat the steering wheel to pieces trying to install a "prettier" one . He even cut the wires to the airbag with a knife while it was still hooked up:nono: . lol:grinyes:
Back to my question for ya. Did you check the resistance with the switch on or off or, where did you find the instructions to do it. Any help would be appreciated..
Thanks Steve...
Oh yeah almost forgot. He also removed all the warning bulbs from the back of the instrument cluster for some odd reason. So, I don't know about a security light..:uhoh:

Chevy-SS
03-26-2008, 08:00 AM
Yes, I installed resistor only, nothing else. It was very easy to do. I just tried the web page that had the instructions, but the page is no longer up, dangit. I am searching my computer to see if I saved a copy of the page. If so, I will post it up for download.


I'll keep looking for the instructions.

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Chevy-SS
03-26-2008, 08:06 AM
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http://www.passlock2.com/

Found some instructions! This is a very nice page. The top section is the one you want, I believe.

Good luck

:wink:

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woodbite
03-26-2008, 05:55 PM
Thanks SS. Figured out his problem last night.
He had pulled out the bulb for security light in the instrument panel. I replaced the bulb. Truck still would not crank but, the fuel pump was still running after it went immediatley dead. (Before the fuel pump would quit running). So i checked the fuses by the door again and he had removed one since the first night I looked at it. The fuse was for the guages. Replaced it. Still wouldn't crank. So I tried the deal were you leave the ign switch on for ten minutes.(4th try with that). It worked. ahhhhh
Just wanted to say thanks for the orignal post with out it I would have been lost.. THANKS
Quite a hair puller!

woodbite
03-26-2008, 05:57 PM
If his truck does this again i will install the resistor. thanks..:grinyes:

Chevy-SS
03-27-2008, 06:58 AM
Cool man, glad u got it. If it still (occasionally) won't start, do the resistor bypass...................

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ss#4
11-19-2008, 04:01 PM
Chevy-SS, Did you ever find the link or directions for this? Any reason a 99 k1500 would be any different than the 98s??

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