LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

VATS bypass vs. New ignition cylinder and key

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Old Jul 9, 2016 | 03:30 PM
  #1  
5.7ftdeep's Avatar
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VATS bypass vs. New ignition cylinder and key

Torn on what to do, go the cheap route with the Bypass or replace the ignition cylinder. Thoughts?
Old Jul 9, 2016 | 05:08 PM
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Re: VATS bypass vs. New ignition cylinder and key

What is the reason for wanting to do the bypass/Cylinder replacement?
- Lost key?
- Lost key pellet?
- Key doesn't satisfy the TDM?
- Lock cylinder needs replacing?

If you change the cylinder you'll still need to do the bypass, because the new cylinder will include a key with no pellet. You may have other options depending on the reason for change.
Old Jul 9, 2016 | 06:59 PM
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Re: VATS bypass vs. New ignition cylinder and key

I have the security light issue and my ignition is cylinder is really loose with a lot of play in it.
Old Jul 9, 2016 | 08:15 PM
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Re: VATS bypass vs. New ignition cylinder and key

If your key is one that worked w/o a security light in the past, and has the pellet, you can measure the resistance value of the pellet and use a resistor of the same value (or very close) for the VATS bypass.

Courtesy of Shoebox
4th Gen LT1 F-body Tech Articles

Then you'll be all set if/when you replace the lock cylinder.
Old Jul 9, 2016 | 08:27 PM
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Re: VATS bypass vs. New ignition cylinder and key

thank you for the reply, I was thinking that my security light issue was just a broken or frayed wire in the lock cylinder or just key not making good contact inside the cylinder and that replacing it would eliminate the security light. I must be off with that thinking then? I should probably go reread about the Vats.
Old Jul 9, 2016 | 08:34 PM
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Re: VATS bypass vs. New ignition cylinder and key

You are correct in that the key cylinder is probably the problem. The thin metal contacts get worn or broken or the wires get loose or broken. It's just that most folks don't want to do the tough job of replacing it and opt for the bypass. You won't need to do a bypass if you replace it, because your current key has the resistor value. You just have to measure it and buy a $10 blank off eBay with the same value then have that cut to match the new cylinder's key. I got my extra key cut by Home Depot for free.

Last edited by GaryDoug; Jul 9, 2016 at 08:37 PM.
Old Jul 9, 2016 | 10:32 PM
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Re: VATS bypass vs. New ignition cylinder and key

Do some testing to verify what the problem really is, then proceed from there.
Old Jul 10, 2016 | 07:53 AM
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Re: VATS bypass vs. New ignition cylinder and key

Using Shoebox's diagram, separate the connector for the key cylinder leads, and measure the resistance at the connector pins, with the key in the cylinder. Should be close to the value measured directly on the key pellet.

http://shbox.com/1/vats_bypass.jpg
Old Jul 10, 2016 | 12:37 PM
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Re: VATS bypass vs. New ignition cylinder and key

Thanks guys, good looking out. I haven't used my multi-meter for many years and discovered a battery has leaked all over inside and corroded so I will have to purchase a new one today. Any suggestions on a descent digital multi?
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