How to Bypass your VATS

**pajeff02** · 01-10-2015, 03:57 PM

Is it cranking, or not doing anything when you turn the key?

**CORYSTA** · 01-10-2015, 04:32 PM

Originally Posted by pajeff02

Is it cranking, or not doing anything when you turn the key?

Not cranking at all.

Everything works great when the ignition is turned to ACC or RUN. When I turn it to start it doesn't do anything. It doesn't try to start at all.

**pajeff02** · 01-11-2015, 04:31 AM

Ok - totally agree then with what 0rion posted. Only other thing would be to verify your key resistance and your bypass resistance. Depending upon the resistors you used, there can be anywhere from a 5% to 10% variance in stated vs. actual resistance.

**CORYSTA** · 01-11-2015, 06:54 AM

I did that before I installed it and it was the first thing I did after the problem started.

**CORYSTA** · 01-11-2015, 07:54 AM

Oh sorry I just went back and reread Orion's post. I completely disconnect the Viper wires from the vehicle yesterday. Tried both BCMs and still nothing.

**pajeff02** · 01-11-2015, 08:09 AM

Something may have been missed in the disconnect process. A ground perhaps?

**CORYSTA** · 01-11-2015, 08:21 AM

Originally Posted by pajeff02

Something may have been missed in the disconnect process. A ground perhaps?

I did leave the Viper Power and Ground (And parking lights pain in the but to get to) connected, but with how I connected them I don't see how they could be interfering with anything.

My power (for the Viper Alarm, not Remote Start) is connected to the empty battery slot in the fuse box.

My ground is connected to the ground stud on the passenger side behind the kick panel. I didn't touch the factory ground setup up. It's a stud that has a lot of thread left. So I took an eyelet, placed it on the stud against the factory nut that secures the ground connection. Then I took another nut and secured my ground to the stud. Alright it sounds like this needs a picture. I'll get one.

**kingls1** · 01-13-2015, 05:41 AM

Weird thing happened to me when I used the factory ground bolt with my volt meter to check something. I could NOT get a ground from the bolt as it seems to have a coating on it. The only way I got ground was going through wire with probe. Just a thought to check.

**CORYSTA** · 01-13-2015, 01:06 PM

Originally Posted by kingls1

Weird thing happened to me when I used the factory ground bolt with my volt meter to check something. I could NOT get a ground from the bolt as it seems to have a coating on it. The only way I got ground was going through wire with probe. Just a thought to check.

Thanks for the suggestion. I thought I checked it during the install, but I went and checked again. I'm getting 12V from a constant 12V+ source when using a wire off my ground.

**CORYSTA** · 01-17-2015, 01:53 PM

The security light has stopped flashing.

I had inspected the T connectors on the VATs wires. There was wire exposed, so I assumed I had a good connect.

I took my wire strippers and uncovered a small length of wire for my T connecters to grab ahold of it. As soon as I did this the light stopped blinking :/

well atleast she's running again. Thanks for all the help!!!

**herculesrider1** · 06-18-2015, 07:59 PM

I did the VATS bypass this morning. I cut the white wires close to the connector and inserted one end of the resistor in the lug where one of the white wires was crimped and soldered it. Then inserted the other end of the resistor into the other lug that the other white wire was crimped in, and soldered it in. I left the white wire connector connected to the purple/black and white/black connector. This way, if I ever get the ignition switch replaced, the switch comes with the two white wires and connector. All I would have to do is disconnect the white wire/resistor connector and plug in the new white wire connector from the new switch. I could then keep the white wire/resistor connector in the glove box, just in case the switch started acting up again! Whatever you do, DON'T insert the resistor in one of the connectors AND reconnect the two connectors. If you do this, the BCM will be reading your resistor AND your key, will get an erroneous double reading and will not start. For example, if your key has a 1.13 ohms resistor value, and you installed a 1.13 ohm resistor in one of the connectors AND reconnected the connectors to each other, when you put your key in, you would get 2.26 ohms due to the key resistor value AND the resistor resistance value because they would be in series and would add up. Your BCM is looking for 1.13, and when it does not read that value, it won't allow the car to start. Note: the resisance value must get back to the BCM via the purple/black, white/black wires. You cannot attach the resistor to the white wires and leave the purple/black, white/black connector disconnected from the white wire connector. The BCM is connected to the purple/black, and white/black wires.

**79Firebird_99TA** · 06-19-2015, 01:10 PM

Originally Posted by herculesrider1

I did the VATS bypass this morning. I cut the white wires close to the connector and inserted one end of the resistor in the lug where one of the white wires was crimped and soldered it. Then inserted the other end of the resistor into the other lug that the other white wire was crimped in, and soldered it in. I left the white wire connector connected to the purple/black and white/black connector. This way, if I ever get the ignition switch replaced, the switch comes with the two white wires and connector. All I would have to do is disconnect the white wire/resistor connector and plug in the new white wire connector from the new switch. I could then keep the white wire/resistor connector in the glove box, just in case the switch started acting up again! Whatever you do, DON'T insert the resistor in one of the connectors AND reconnect the two connectors. If you do this, the BCM will be reading your resistor AND your key, will get an erroneous double reading and will not start. For example, if your key has a 1.13 ohms resistor value, and you installed a 1.13 ohm resistor in one of the connectors AND reconnected the connectors to each other, when you put your key in, you would get 2.26 ohms due to the key resistor value AND the resistor resistance value because they would be in series and would add up. Your BCM is looking for 1.13, and when it does not read that value, it won't allow the car to start. Note: the resisance value must get back to the BCM via the purple/black, white/black wires. You cannot attach the resistor to the white wires and leave the purple/black, white/black connector disconnected from the white wire connector. The BCM is connected to the purple/black, and white/black wires.

Not correct on the electronic math. The resistance would be half not double because the resistor would be parallel with the key's resistance; not in series. The contacts aren't "reading" the key's resistance anyhow (open circuit) which is why one is in there doing the work to begin with.

... I too would not backfeed the connector with the resistor(s) and leave it like that.

**Tomicich** · 11-16-2016, 03:31 PM

Great thread, thanks to everyone with input. I actually had my security light on but the car still started for 4 months, I figured it wasn't VATS because the car started. After 4 months, my ignition switch (big one on the column, not the key switch) went out and I saw the broken wire while troubleshooting. Initially soldered the broken wire going to the key switch, security light went out but still wouldn't start until the whole ignition switch was replaced. My VATS fix only lasted a few months before one of the wires broke again so I did the VATS bypass.
Used the white wires and soldered in the resistor, covering the whole mess with shrink tubing.

**rel3rd** · 10-18-2018, 11:58 AM

At work, so I cannot read 19 pages worth, lol...

Question:

Can the BCM itself be modified so that there it doesn't "need to see" the resistor, and so there is no possibility of having a relapse of these resistor related no-start conditions?

My 2000 Trans Am randomly, and with no pattern whatsoever, has a "Security" light on, no crank issue.

I plan to do the resistor mod ASAP after finding a resistor, but would prefer to "fix it" permanently and never have to worry about it again.

Right now, it is starting, but SECURITY light stays ON for 3-5 seconds after car starts...

Car is a bracket racer, so on any given race day, may be started 10-20 times, so I have to rely on it starting.

Today, I simply went to fire it up and unload it from the trailer, and tried every little trick I could think of, or read about on Google, lol

Any insight appreciated!

***SMWS6TA*** · 10-18-2018, 12:34 PM

the resister mod fixes it permanently in that it will get the correct ohm's range ready.

However if the solder on the bcm cracks it creates other issues. There is a fix for that too, you just need to be good at soldering and not burn the bcm circuit board.

IIRC a stand alone harness with the ecm programmed to not look for the bcm is about the only way to bypass it entirely.

**rel3rd** · 10-18-2018, 01:11 PM

Originally Posted by SMWS6TA

the resister mod fixes it permanently in that it will get the correct ohm's range ready.

However if the solder on the bcm cracks it creates other issues. There is a fix for that too, you just need to be good at soldering and not burn the bcm circuit board.

IIRC a stand alone harness with the ecm programmed to not look for the bcm is about the only way to bypass it entirely.

Thanks for the reply. I always "assumed" since the VATS was turned off in my tune, I'd never have any trouble...but that doesn't seem to matter. Will do the resistor mod, and hope that's the end of it.

Just need to locate a resistor...only ones I am seeing online are packs of 50 or 100. I'd hate to spend 10 bucks on something that everyone else has spent pennies on, but it wouldn't be the first time, lol.

Thanks again

**rel3rd** · 10-22-2018, 03:41 AM

Just to update...

Ordered a complete 15 piece "pellet" matching GM resistor "kit" off of Amazon, and while searching for the VATS connection, discovered it had already been modified at some point, via a twisted together, hack job of an aftermarket alarm install...

Since connector had been cut off, I chose to make up a nice, soldered resistor bypass, and used a small weatherpack connector to plug it in....

Of course, this was after chopping out all of the un-needed, non-functioning aftermarket alarm butchery...

Started every time all weekend, so hoping it's "fixed"

Thanks...

**herculesrider1** · 10-22-2018, 11:31 AM

Don't you hate hack jobs? I just bought another 2000 Trans Am for my wife, and have found things that I am ashamed of for even being on the car. Previous owners....don't ya just love them? I come from training that says, "Do it right, or just stay home". Glad you got it fixed "Right"...!!

**rel3rd** · 10-22-2018, 12:56 PM

Originally Posted by herculesrider1

Don't you hate hack jobs? I just bought another 2000 Trans Am for my wife, and have found things that I am ashamed of for even being on the car. Previous owners....don't ya just love them? I come from training that says, "Do it right, or just stay home". Glad you got it fixed "Right"...!!

Definitely is annoying re-doing almost every single added on, or modified, item on a newly acquired car. I have had this car almost a year, and HOPE, that I am finally done fixing all of the last guys stuff, lol.