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-   -   Defeat VATS Without Modifying PROM? (https://www.thirdgen.org/forums/diy-prom/37394-defeat-vats-without-modifying.html)

87/88Firetruck 01-12-2001 04:45 PM

Defeat VATS Without Modifying PROM?
 
Apparently, most people who do not wish to deal with the GM VATS have all the VATS-associated equipment on the vehicle, and the greatest challenge is finding a resistor which matches the one in the original key. Unfortunately, I do not have such luxuries. I am trying to get around a 1986 'vette VATS, and all I have is ECM 1227165 and the original PROM. I found somewhere that a 50hz signal is emitted on the ignition circuit by the VATS decoder module, and that this can be created using an oscillator. Does this seem plausible to anyone? I am not having problems with the starter, since that circuit is independent, but the injectors on my system shut off after about 2 seconds and the ECM stores code 46. Any ideas on how I can get around this? My installation is from a 1987 L98 GTA, and I am using it in a 1988 GMC 1/2 ton truck. If the Passkey systems from 1986-1989 are similar, any reasonably simple means of defeating VATS would be useful, since this would enable me to use any MAF ECM. Thanks.

Blade 01-12-2001 05:18 PM

Burn another chip with the VATS disabled. Simple as that...

Grumpy 01-13-2001 03:19 PM

Quote:

Originally posted by 87/88Firetruck:
Apparently, most people who do not wish to deal with the GM VATS have all the VATS-associated equipment on the vehicle, and the greatest challenge is finding a resistor which matches the one in the original key. Unfortunately, I do not have such luxuries. I am trying to get around a 1986 'vette VATS, and all I have is ECM 1227165 and the original PROM. I found somewhere that a 50hz signal is emitted on the ignition circuit by the VATS decoder module, and that this can be created using an oscillator. Does this seem plausible to anyone? I am not having problems with the starter, since that circuit is independent, but the injectors on my system shut off after about 2 seconds and the ECM stores code 46. Any ideas on how I can get around this? My installation is from a 1987 L98 GTA, and I am using it in a 1988 GMC 1/2 ton truck. If the Passkey systems from 1986-1989 are similar, any reasonably simple means of defeating VATS would be useful, since this would enable me to use any MAF ECM. Thanks.
33-66 50%DC 5v signal
Double the speed and use a flip flop to get the 50% DC

555 running off a 7805 (?) it's a little 3 pin voltage regulator. Use a 10 Mfd cap on the Input side to the 555.



raven350 01-13-2001 03:58 PM

Permenantly Ground the relay.....

garvinshawn92 04-24-2011 03:54 PM

Re: Defeat VATS Without Modifying PROM?
 
how do or what to do by grounding relay permanately

garvinshawn92 04-24-2011 03:58 PM

Re: Defeat VATS Without Modifying PROM?
 
im having the same problem with the code 46 everything work except injectors arent feeding the fuel really aggrevating beings my car is stuck in front of gmas house and people have been trying to break in to it really sux

DENN_SHAH 04-25-2011 10:28 PM

Re: Defeat VATS Without Modifying PROM?
 
odds are the VATS wiring going to the key lock cylinder are bad near the lock cylinder. its a very common problem with the VATS.
if that is in fact your problem, you can replace the lock cylinder and get 2 new ignition keys to match the resistor of your old keys but cut for the new cylinder.
or you can build a bypass harness to bypass the lock cylinder.
you can get or build a bypass module that would make the ECM think the VATS system is working, but you would also have to bypass the starter relay.
you can have the VATS removed from the chip by burning a new chip with VATS disabled, again you would also have to bypass the starter relay.

if you do decide to replace the lock cylinder, be certain to buy a Delco lock
cylinder. the aftermarket lock cylinders are trouble prone and won't last like they should. where i used to work at, we tried the aftermarket cylinders a few times and always had to replace them within a few months with Delco lock cylinders and keys.

2 good pages of VATS info and trouble shooting,
https://www.thirdgen.org/vats

https://www.thirdgen.org/vats_passkey_system


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