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what kind of resistors do i need VATS

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Old 01-16-2010, 11:49 PM
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Default what kind of resistors do i need VATS

so i found out that my key code is pellet code 8 and should be at 2370 ohms. i was looking at radioshacks website and they have (1/4) and (1/2) watt resistors which should i go with. and should i get a variety pack and just experiment with ohms.
thanks alot oh and where else can i get resistors.
Old 01-17-2010, 01:57 AM
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1/2 watt resistors will work just fine.

From what I can find, you could try getting a 2.2k and a 150 ohm resistor. This will give you 2350 which is pretty damn close.
Old 01-17-2010, 02:05 AM
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oh ok i see and then i just run them parralel right, but my plan is to run to the resistors then to a switch which i will hide somewhere so i can still disable my car unless you know where the switch is.
im pretty new with ohms and resistors, but i have done alot of wiring so it shouldnt be hard at all right. pretty much im just running a switch with resistors in between
Old 01-17-2010, 04:59 AM
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Yeah not hard at all.

STOCK:
-----------|=======|---------------\
Dash______Connector______________Key
-----------|=======|---------------/


BYPASS (KILL SWITCH):
-----------|=======|-----~2.2k~-----\-----<cut>----\
Dash______Connector________________KILL___________Key
-----------|=======|-----~150 ~-----/-----<cut>----/

The placement of everything could be changed anyway you want, does not really matter as long as the signal goes through the resistors.

Last edited by 7th Darkness; 01-17-2010 at 05:06 AM.
Old 01-17-2010, 05:33 AM
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So I'm missing something here....

A 2200 Ohm resistor and a 150 Ohm resister in parallel doesn't give you 2350 Ohms; it gives you 140.426 Ohms. So why are you paralleling them?

And how accurate does the value need to be to not trip the VATS system?
Old 01-17-2010, 06:00 AM
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Originally Posted by Darker Shadow
So I'm missing something here....

A 2200 Ohm resistor and a 150 Ohm resister in parallel doesn't give you 2350 Ohms; it gives you 140.426 Ohms. So why are you paralleling them?

And how accurate does the value need to be to not trip the VATS system?
Want to run them in series not in parallel. Value is +/- 5%

Last edited by 7th Darkness; 01-17-2010 at 06:08 AM.
Old 01-17-2010, 03:39 PM
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This should help you see the range you can use.
http://shbox.com/1/4th_gen_tech2.html#pass_key
Old 01-17-2010, 05:54 PM
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yea thanks im in the range but another question is it ok to just solder the resistor to a wire on each side and then just wrap the whole thing with electrical tape to protect it. these resistors shouldnt get that hot right. its probably barely any current going through it so im guessing it wont get hot and should be fine.
Old 01-18-2010, 03:17 PM
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Originally Posted by 96TransAmM6
hey man if you want to do it the easy way the first time just do this. under your dash you will have the vats wires. in most cases its a yellow wire next to an orange wire with a black stripe. start the car then cut the yellow wire in half and strip both ends, strip back the orange and black wire so you can put your test lead on it. the security light should come on once you cut the yellow wire letting you know you cut the right wire. leave the car running while you measure resistance from the key side of the yellow wire with the positive lead and put your negative lead on the orange/black wire. this will tell you the exact resistance needed to bypass the vats. once you have the correct number turn the car off. now using your multimeter wire it to the variable resistor and set it to the exact resistance. once you do that solder one side of the resistor to the bcm side of the yellow wire (not key side) and the other end of the resistor to the orange black wire. just tape up the keyside of the yellow and start the car. should start right up with no security light. if you dont have the yellow and orange black wires they will be 2 white wires next to each other. do the same thing as above but read the wires with a meter to determine which wire is the ground and which is the resistance.
HUH???? Why go to all that trouble when you can just take your ohmmeter and directly measure the resistance between the contacts on opposite sides of the key. No wires to cut and you can do it in the comfort of your living room.

Once you've determined the resistance of your key pellet, find the closest value in the table of allowed resistance values posted on this site and countless other websites (there are 15 values but f-bodies only used 14 of them). THEN you can worry about cutting the wires and splicing in the correct resistors.

There is a kit that automates much of the installation process. It is called the Omega IB-PLIX and it is self-learning but it is designed for use with remote starters rather than as a permanent bypass. It retails for $64 but I have seen it as cheap as $22.
Old 01-18-2010, 04:04 PM
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I really don't want to get into a pissing match here but I don't want misleading information out there either. Your way assumes that you have all the necessary resistors on hand because once you cut the wires, you're not going out to buy them in that car. It may work fine in a shop with everything in stock but it's not the best way for a backyard mechanic.

If you get a different reading each time you check the resistance of the key pellet then you need a different ohmmeter or better skills. When you do it your way, you are still reading the resistance of the key pellet - you're just adding the wiring in between. So what would make you think that it would be different than measuring directly at the key? That's an electrical impossibility.
Old 01-18-2010, 06:32 PM
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i got it workin today and the switch works perfect off and it wont start on and it starts. its just like a security feature. you answered my question about soldering a wire right to a resistor that works fine but im still wondering if i should worry about the resistor getting hot and melting the electrical tape. i measured how many volts go through the wire and its almost 6 volts. what do you think
Old 01-19-2010, 07:30 AM
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Originally Posted by 96TransAmM6
lol well then i guess you just started a pissing match.....how many vats systems have you bypassed? i have done hundreds. so misleading information from me? i dont think so buddy. most people on internet forums have little to no actual experience. im just posting because i do know and can help. if you knew what a variable resistor (Potentiometer) was you would know that you dont need any amount of resistors on hand. you can adjust a single resistor to any resistance up to 3000-5000 ohms if you need more you can ad more variable resistors to increase the value. now as far as your otehr claim. here is you explanation. the vats resistance is coded into the bcm and the key just matches the value. so the resistor contacts on the key can easily get worn out over years of use and by putting your test leads on the chip its only so accurate between the two posts. even so you need to match the bcm resistance which will never change thats why alot of peoples vats have problems because their keys wear out. again i just posted up to help and your not even the one needing the help?
Sorry, I was having a bad day yesterday and could have worded that more diplomatically. I realize you were trying to help. My point is that doing something in a well equipped shop is completely different than doing it for the first time in your driveway. The poster would not likely have a pot or multiple resistors on hand so measuring the key without cutting any wires and then going to get the necessary parts is the way it's usually done.

However, your explanation is either badly worded or you don't understand the electrical circuits behind it. The BCM has no resistance on the VATS circuit. It measures the resistance on the circuit by comparing the reference input voltage to the return voltage. The expected resistance is programmed into the BCM the first time it is used and can't be changed after that. Bypassing the VATS is a process of substituting another source of resistance for that of the original ignition key. You are correct that the key pellet contacts can get worn over years of use but that does not affect its resistance, only its ability to make a good connection to the contacts inside the ignition cylinder. You can still get a good resistance value directly from the key contacts. And you don't have to be precise - there's a 10% variance allowed in the system. That's why I suggested looking up the closest matching value in the table rather than trying to precisely match the measured reading. Besides, if the contacts are worn enough that they don't make good connection with the ignition cylinder contacts then your method won't work at all - you'll be trying to read the resistance the same way the BCM does (through the ignition cylinder) and get the same faulty reading that caused the BCM to reject the key in the first place.

BTW, I may have only done a few dozen VATS bypasses because it's my hobby not my job but I think you'll admit that my degree in electronics and 35 years experience qualify me to comment (and yes, I know what a potentiometer is ).
Old 01-19-2010, 09:39 AM
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Originally Posted by 96TransAmM6
if you have been doing this for 35 years i dont know what to tell you man i didnt know they had a mobile electronics industry back in nam! jk broski
Sure there was - lots of people wanted 8-tracks and alarms then.

Actually, in the mid 70s I worked for a company that customized vans with stereo systems, CB radios (Smokey and the Bandit dontcha know), handicapped access equipment (lifts, etc.), alarms, cruise controls, and various custom lighting.



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