Vats
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From: Louisiana
Vats
Does anyone have info on how to bypass the VATS system/module? I'm not talking about the stupid little resister key pellet bypass which only bypasses the key, but NOT the vats module/system. I'm talking about the VATS module itself, I want to know how to bypass the vats module in case case the the vats module/system fails (in which case the resister bypass is useless).
Safety Car
Joined: Aug 2009
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From: Melbourne, Victoria, Australia
Does anyone have info on how to bypass the VATS system/module? I'm not talking about the stupid little resister key pellet bypass which only bypasses the key, but NOT the vats module/system. I'm talking about the VATS module itself, I want to know how to bypass the vats module in case case the the vats module/system fails (in which case the resister bypass is useless).
There are a few options, see links below. Once you have measured the key resistance, to obtain the correct code to bypass the system. Obviously good to have this before you have issues, so you have a way around it when it fails so you don't get stranded. 🙂👍
http://www.corvettecentral.com/c4-84...991%26q%3dvats
https://www.corvettecentral.com/c4-8...1%26q%3dvats%2
Melting Slicks
Joined: Nov 2016
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From: So Cal
2023 C4 of the Year Finalist - Unmodified
He has a 1989. Use a signal generator. Bypass the relay if it hasn't already been done decades ago.
Last edited by IHBD; Oct 14, 2025 at 08:03 PM.
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Joined: Sep 2024
Posts: 50
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From: Louisiana
Hi
There are a few options, see links below. Once you have measured the key resistance, to obtain the correct code to bypass the system. Obviously good to have this before you have issues, so you have a way around it when it fails so you don't get stranded. 🙂👍
http://www.corvettecentral.com/c4-84...991%26q%3dvats
https://www.corvettecentral.com/c4-8...1%26q%3dvats%2
There are a few options, see links below. Once you have measured the key resistance, to obtain the correct code to bypass the system. Obviously good to have this before you have issues, so you have a way around it when it fails so you don't get stranded. 🙂👍
http://www.corvettecentral.com/c4-84...991%26q%3dvats
https://www.corvettecentral.com/c4-8...1%26q%3dvats%2
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Joined: Sep 2024
Posts: 50
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From: Louisiana
I have yet to pull the dash panels, but I can here the starter relay in the dash clicking when i turn the key so i'm sure the starter relay has not been bypassed yet, but sometimes (intermittently and unpredictably) the car won't turn the starter even though I can here the starter relay click. Also intermittently, the "security" starts flashing when I try to crank. sometimes the car cranks fine but randomly, the starter will not turn or engage the starter solenoid. I checked and when the problem happens, no power is sent to the starter. So I want to completely cut the VATS module out to be sure that doesn't leave me stranded if it should happen to go bad. Even if that is not the current problem, It will cut it out so it never becomes a problem just to be sure. The other reason is if that vats module goes out, the care will still not crank even though the starter relay is bypassed, because even if though starter will turn, it won't send the signal to the ECM to fire the injectors. So I was wondering if there was a way to jump power so that the ECM is also fooled if the vats is not working.
Last edited by CajunCatholic; Oct 14, 2025 at 08:43 PM. Reason: spelling correction
Melting Slicks
Joined: Nov 2016
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From: So Cal
2023 C4 of the Year Finalist - Unmodified
If you CAN hear the relay click (and you are CERTAIN that the relay you hear is the starter relay) the VATS module IS energizing the relay. In a 1986-1989, the relay contacts are Normally Open, and the VATS module provides a ground to close the contacts when the key is in CRANK. If the starter relay is clicking, the module is providing the necessary ground. << It is not "VATS". But it COULD BE the relay contacts. Ie, the relay is bad.
You report that there is no power at the starter. There are other possibilities. After the relay, the circuit goes through the P/N switch (automatic) or the clutch safety switch (manual). If you have a 6-speed, the clutch safety switches are known to be problematic.
Another diagnostic for when it will not crank, pull the codes. Check for the presence of Code 46. If Code 46 is NOT present, it is NOT "VATS".
So I was wondering if there was a way to jump power so that the ECM is also fooled if the vats is not working.
Here's a picture of it:
Last edited by IHBD; Oct 15, 2025 at 11:52 AM.
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From: Louisiana
Thanks.,,, I found the problem. It was the clutch safety switch. I was looking at the wrong switch. There are 2 switches on the clutch pedal. The first switch you see is the cruise control disengage. You have to look much higher up to the top at the pivot point to find the starter safety switch. I pulled the plug and jumped it, then it started immediately.
Thanks for the nice part picture of the bypass timer. I went to site address on part in the pic and found it. That's exactly the kind of thing i was looking for but didn't know where to find it so thanks again.
Thanks for the nice part picture of the bypass timer. I went to site address on part in the pic and found it. That's exactly the kind of thing i was looking for but didn't know where to find it so thanks again.
Last edited by CajunCatholic; Oct 15, 2025 at 12:47 PM. Reason: spelling
Melting Slicks
Joined: Nov 2016
Posts: 2,256
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From: So Cal
2023 C4 of the Year Finalist - Unmodified
The clutch safety switch is a fairly common problem on here.
Your VATS system will probably continue to operate in the future as reliably as it already has for the past 36 years. It may have a resistor bypass from a previous owner. Did you happen to look while you were under there with the clutch switch?
Your VATS system will probably continue to operate in the future as reliably as it already has for the past 36 years. It may have a resistor bypass from a previous owner. Did you happen to look while you were under there with the clutch switch?
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Melting Slicks
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IHBD, you know your stuff with these old cars, man. I find your content to be very useful, even if only in terms of gathering knowledge I didn't previously have about some things.
Burning Brakes
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I second that. I know my way around a classic sbc, but IHBD is always dropping nuggets with how these motors interact with the various modules. Much appreciated
