Struggling with VATS bypass
Thread Starter
Teching In
Joined: May 2010
Posts: 39
Likes: 0
Launching!
Joined: Mar 2004
Posts: 223
Likes: 0
From: Apple Maggot Quarantine Zone
Can you try leaving the battery unhooked, key to the run position, and then reconnect the negative.
May be able to power up the car without the system coming online the first time.
BTW, I would unhook the horn wire so that you can work on it without driving your neighbors up the wall...
May be able to power up the car without the system coming online the first time.
BTW, I would unhook the horn wire so that you can work on it without driving your neighbors up the wall...
11 Second Club
Joined: Sep 2015
Posts: 276
Likes: 51
Is this a new problem with the vehicle. Are you sure this is the original ign key for the vehicle. If disconnecting the VATs connector at the column and jumping it with a resistor dosnt start the car, perhaps you have a wiring issue or perhaps the BCM is no good on your car.
Thread Starter
Teching In
Joined: May 2010
Posts: 39
Likes: 0
Yeah I'm thinking there is something bad with the connection or the BCM. The car's had the security light issue for a while now and now it seems it finally bit the dust. I bought a 50 hz module send the signal to the PCM for the fuel injectors. If I install this and bypass the TDR (theft deterrant relay that engages the starter), do you think my car will start? I'm honestly just piecing together other problems that people have had and most go to the module after the resistor method failed.
Joined: Nov 2003
Posts: 11,329
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
The theft deterrent relay does not connect to the starter... it simply handles flashing the parking lights when an alarm has been triggered.
The two things you have to do to keep VATS from preventing starting is to ground the starter relay coil output (yellow/black wire) and fix the lack of a fuel enable signal from the BCM to the PCM - that is generally done using a tuner.
That will still leave the SECURITY light on your dash. A properly implemented VATS bypass takes care of all three.
The two things you have to do to keep VATS from preventing starting is to ground the starter relay coil output (yellow/black wire) and fix the lack of a fuel enable signal from the BCM to the PCM - that is generally done using a tuner.
That will still leave the SECURITY light on your dash. A properly implemented VATS bypass takes care of all three.
Thread Starter
Teching In
Joined: May 2010
Posts: 39
Likes: 0
So, does that mean the starter is bad? I grounded the yellow black wire and nothing happened. The alarm was still engaged, honking and lights going.
Edit: I got the alarm reset. But still nothing when the wire is grounded and I try to start it.
Edit: I got the alarm reset. But still nothing when the wire is grounded and I try to start it.
Last edited by Snowman5677; Jan 4, 2016 at 06:17 PM.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Thread Starter
Teching In
Joined: May 2010
Posts: 39
Likes: 0
Woo hoo! Got it started. Turns out I had a bad ground from the yellow/black. I'm confused because I swapped every single fan relay for the starter and ignition relays and still got nothing.
Edit: Welp, only got 2 starts out of that. Tried disconnecting the battery and wiring the yellow/black back in and all I hear is a knock. Tried putting the ground back in and I can't get it to start from that either.
Edit: Welp, only got 2 starts out of that. Tried disconnecting the battery and wiring the yellow/black back in and all I hear is a knock. Tried putting the ground back in and I can't get it to start from that either.
Last edited by Snowman5677; Jan 4, 2016 at 07:16 PM.
Registered User
Joined: Feb 2021
Posts: 1
Likes: 0
Remove Horn Relay Things have only continued to go downhill for my car. Tried grounding the starter relay to see if I could get it to crank and now the car is just stuck in alarm activated mode. Before the door alarm was set but now the car just starts honking as soon as you hook up the battery. I hate VATS and I'm going insane.
Don't know if you're still on here but thanks for sharing...
It looks to me like I can disable the VATS on the PCM in HPTuners so the BCM will no longer comand fuel and then ground C11 from the BCM to allow the starter relay to start the car thus bypassing the stupid VATS system. I'd hate to be up on the starting line only to have a no start because a resistor decided to fail on me.
It looks to me like I can disable the VATS on the PCM in HPTuners so the BCM will no longer comand fuel and then ground C11 from the BCM to allow the starter relay to start the car thus bypassing the stupid VATS system. I'd hate to be up on the starting line only to have a no start because a resistor decided to fail on me.
Joined: Nov 2003
Posts: 11,329
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Don't know if you're still on here but thanks for sharing...
It looks to me like I can disable the VATS on the PCM in HPTuners so the BCM will no longer comand fuel and then ground C11 from the BCM to allow the starter relay to start the car thus bypassing the stupid VATS system. I'd hate to be up on the starting line only to have a no start because a resistor decided to fail on me.
It looks to me like I can disable the VATS on the PCM in HPTuners so the BCM will no longer comand fuel and then ground C11 from the BCM to allow the starter relay to start the car thus bypassing the stupid VATS system. I'd hate to be up on the starting line only to have a no start because a resistor decided to fail on me.
A properly wired and secured VATS bypass will last basically forever. I did one in my T/A and had it without failure for almost 10 years, and as far as I know the guy who bought the car is still running it without change another 10 years later. The bypass takes care of the security light in the dash as well, doesn't require rewiring the starter relay, and doesn't involve any PCM programming. All in all, a good solution for the cost of a couple of resistors (literally pennies) and maybe an hour of your time.
Ah, thank you for that. I wasn't sure so I was going to try it and see but I ended up putting a resistor on the PPL/WHT and WHT/BLK and was able to bump the starter over.
Registered User
Joined: May 2023
Posts: 1
Likes: 0
Two completely separate issues. The power windows and radio issue is caused by an intermittent failure of the retained accessory power (RAP) circuit in the BCM which in turn is commonly caused by a bad solder joint on the circuit board of the BCM. There is a simple fix here: https://ls1tech.com/forums/general-m...blems-fix.html.
The SECURITY light in the instrument cluster is controlled by VATS. If it detects an invalid resistance value from the ignition key, the light will be solidly lit. If it fails to detect any resistance value, the light will be flashing. If the failure occurs while the engine is already running then the system assumes a fault and will still allow the car to be restarted. Otherwise, the system will disable both the starter relay and the fuel enable signal from the PCM effectively preventing the car from starting.
Since your car continues to start, the system must be considering the wrong resistance as a system fault. However, you must get it fixed before you disconnect the battery for any reason because when you reconnect the battery it will no longer be considered a fault and your car won't start.
The SECURITY light in the instrument cluster is controlled by VATS. If it detects an invalid resistance value from the ignition key, the light will be solidly lit. If it fails to detect any resistance value, the light will be flashing. If the failure occurs while the engine is already running then the system assumes a fault and will still allow the car to be restarted. Otherwise, the system will disable both the starter relay and the fuel enable signal from the PCM effectively preventing the car from starting.
Since your car continues to start, the system must be considering the wrong resistance as a system fault. However, you must get it fixed before you disconnect the battery for any reason because when you reconnect the battery it will no longer be considered a fault and your car won't start.
What ohm value did you find for the key? An easy way to tell if the wires on the ignition switch has failed is to put a multimeter on each end of the plug connector which has the two white wires with an orange sleeve and check for continuity. No continuity then the connection has been broken.
Solution: Determine the ohm value of the reistor key so you can purchase the correct resistor(s) and either solder onto the PPL/WHT and WHT/BLK wires or cut the lead which has the two white wires, disconnect the connector and solder the resistor(s) between the two white wires and plug it back in. Check the ohm value of the connector prior to connecting it back up to see if it matches the key and if so then you should be good to go.
Still no start? Is the starter relay good and are you getting 12v at the power side of the relay when keyed on to start? If the VATS bypass didn't work and you're not getting a signal to the relay YLW/BLK wire from the BCM then you could have a bad body control module. If everything is working as it should then when you key it on to start you should have 12v at the purple wire coming from the starter relay which goes to the starter solenoid and if so then I'd start looking at your starter.
Solution: Determine the ohm value of the reistor key so you can purchase the correct resistor(s) and either solder onto the PPL/WHT and WHT/BLK wires or cut the lead which has the two white wires, disconnect the connector and solder the resistor(s) between the two white wires and plug it back in. Check the ohm value of the connector prior to connecting it back up to see if it matches the key and if so then you should be good to go.
Still no start? Is the starter relay good and are you getting 12v at the power side of the relay when keyed on to start? If the VATS bypass didn't work and you're not getting a signal to the relay YLW/BLK wire from the BCM then you could have a bad body control module. If everything is working as it should then when you key it on to start you should have 12v at the purple wire coming from the starter relay which goes to the starter solenoid and if so then I'd start looking at your starter.
Joined: Nov 2003
Posts: 11,329
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
Otherwise, either your resistors aren't making a solid connection to the two wires or there is a break in one or both wires between the steering column and the BCM.