VATS tuned out, resistor in and working, still get occasional SECURITY light.
06-05-2021, 11:24 AM
#1
VATS tuned out, resistor in and working, still get occasional SECURITY light. Background: 1999 Trans Am A4 DD with 250k+ miles not worth stealing.
VATS resistors are in place, VATS tuned out of PCM with HPTuners, all was good for last few years but now SECURITY light occasionally coming on SOLID again causing a "no crank" condition (starter won't engage), almost left me stranded AGAIN this morning far from home.
Few years ago car left me stranded almost 100 miles from home at a gas station due to key resistor problem, did emergency resistor VATS fix with purple wire under dash in their parking lot, got me home and I did a very good soldered/shrinkwrapped install of the resistors. This worked for like 2 maybe 3 years, also have VATS tuned out in PCM. Am verifying the resistors again now, but have 2 questions:
1) I hear tale of a way that I can jumper some wires near the passenger shock tower (purple I think) that in an emergency (or when working on the car) I can kick the starter and get the car to turn over. Since I have VATS tuned out of the PCM, would this emergency crank solution get me running if I am far from home and encountering a VATS problem? If so can someone throw me some details?
2) Tried googling but getting a ton of BS Spammy answers, I understand there is a module I can buy that fixes the "controller" side of the BCM (not the resisitor/key "signal" side) so even if the BCM detects a problem the BCM will be unable to prevent the car from starting. Can someone point me to the right way to do this, if possible? Note I probably won't be able to build some of the circuit board solutions I've seen, willing to buy something hopefully not too expensive.
Car is a beat up trans am I paid $4500 many years ago, has over 250k miles and looks it. The VATS problems are not worth the theft protection benefit for this car, please help me find a solution that will allow me to trust this car as a long distance DD again.
Thanks everyone.
VATS resistors are in place, VATS tuned out of PCM with HPTuners, all was good for last few years but now SECURITY light occasionally coming on SOLID again causing a "no crank" condition (starter won't engage), almost left me stranded AGAIN this morning far from home.
Few years ago car left me stranded almost 100 miles from home at a gas station due to key resistor problem, did emergency resistor VATS fix with purple wire under dash in their parking lot, got me home and I did a very good soldered/shrinkwrapped install of the resistors. This worked for like 2 maybe 3 years, also have VATS tuned out in PCM. Am verifying the resistors again now, but have 2 questions:
1) I hear tale of a way that I can jumper some wires near the passenger shock tower (purple I think) that in an emergency (or when working on the car) I can kick the starter and get the car to turn over. Since I have VATS tuned out of the PCM, would this emergency crank solution get me running if I am far from home and encountering a VATS problem? If so can someone throw me some details?
2) Tried googling but getting a ton of BS Spammy answers, I understand there is a module I can buy that fixes the "controller" side of the BCM (not the resisitor/key "signal" side) so even if the BCM detects a problem the BCM will be unable to prevent the car from starting. Can someone point me to the right way to do this, if possible? Note I probably won't be able to build some of the circuit board solutions I've seen, willing to buy something hopefully not too expensive.
Car is a beat up trans am I paid $4500 many years ago, has over 250k miles and looks it. The VATS problems are not worth the theft protection benefit for this car, please help me find a solution that will allow me to trust this car as a long distance DD again.
Thanks everyone.
06-05-2021, 12:22 PM
#2
Can anyone confirm grounding this one wire works as described in this LS1Tech post? I inderstand that it will allow the car to crank, and since I have VATS tuned out in the PCM this should then allow the car to start and run regardless of VATS?
https://ls1tech.com/forums/wiring-st...l#post15055422
Thanks again.
https://ls1tech.com/forums/wiring-st...l#post15055422
There is a yellow/black wire that goes from the starter relay to the bcm. If you cut that wire and ground the end that goes into the relay it will bypass the bcm's control over it.
Last edited by mk3cn4; 06-05-2021 at 12:36 PM.
06-08-2021, 08:46 AM
#3
Allow me to provide a little background on how VATS works and how it can be bypassed to help explain your situation and answer your questions. VATS uses two methods of "preventing" (the quotes are because neither method will deter a professional but they work against amateurs). First, it turns off the ground to the coil side of the starter relay preventing the car from cranking. Second, it disables the fuel enable signal to the PCM so that, even if the car cranks, it will be fuel starved and not continue to run.
The BCM is not programmable and you can't eliminate VATS by programming the PCM to ignore the lack of the fuel enable signal because you still have to contend with the starter relay being disabled. Plus, PCM programming does nothing for the security light in the dash, Doing a VATS bypass using resistors eliminates all of the starting and running protections as well as the security light and actually makes programming the PCM completely redundant.
Now, in your case, because you have done a bypass and the security light has turned on again, it's safe to assume that there is a problem with your bypass. That would not be a break in the circuit because that would cause the security light to flash (unable to see any resistance at all). So that means that there is still continuity in the circuit but that the total resistance is not right. That could be because one of multiple resistors (especially if they had to be wired in parallel) has come loose or it could even be a failed resistor - unusual but it does happen sometimes.
As far as the "emergency" bypass, it is quite true that you can ground a wire to get the car started. This also depends on the PCM having been programmed to ignore the missing fuel enable signal... which you've already done. The idea is to provide a standard chassis ground for the starter relay coil (yellow/black wire) instead of allowing the BCM to control that ground. You can make that ground permanent so that, even if your VATS bypass fails as in this case, you'll still be able to start and run the car - you'll just have the security light to deal with. Or, you could put a switch in the wire to toggle between standard ground and BCM controlled ground. That wouldn't really make any difference as a theft deterrent since the VATS bypass, when working, would provide the ground anyway... even for someone trying to steal the car.
Personally, I would run the yellow/black wire straight to ground since I don't think having any remnants of VATS is worth the risk of getting stranded. Fixing the bypass will take care of the security light but modifying the ground will get the car running in the meantime.
The BCM is not programmable and you can't eliminate VATS by programming the PCM to ignore the lack of the fuel enable signal because you still have to contend with the starter relay being disabled. Plus, PCM programming does nothing for the security light in the dash, Doing a VATS bypass using resistors eliminates all of the starting and running protections as well as the security light and actually makes programming the PCM completely redundant.
Now, in your case, because you have done a bypass and the security light has turned on again, it's safe to assume that there is a problem with your bypass. That would not be a break in the circuit because that would cause the security light to flash (unable to see any resistance at all). So that means that there is still continuity in the circuit but that the total resistance is not right. That could be because one of multiple resistors (especially if they had to be wired in parallel) has come loose or it could even be a failed resistor - unusual but it does happen sometimes.
As far as the "emergency" bypass, it is quite true that you can ground a wire to get the car started. This also depends on the PCM having been programmed to ignore the missing fuel enable signal... which you've already done. The idea is to provide a standard chassis ground for the starter relay coil (yellow/black wire) instead of allowing the BCM to control that ground. You can make that ground permanent so that, even if your VATS bypass fails as in this case, you'll still be able to start and run the car - you'll just have the security light to deal with. Or, you could put a switch in the wire to toggle between standard ground and BCM controlled ground. That wouldn't really make any difference as a theft deterrent since the VATS bypass, when working, would provide the ground anyway... even for someone trying to steal the car.
Personally, I would run the yellow/black wire straight to ground since I don't think having any remnants of VATS is worth the risk of getting stranded. Fixing the bypass will take care of the security light but modifying the ground will get the car running in the meantime.
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mk3cn4 (06-11-2021)
06-11-2021, 09:41 AM
#4
*fixed* Again thanks to this forum and its members, I am up and running.
Thank you for all the information, I have an update and one more question if you don't mind.
Question: If I buy a BCM from Ebay (or someone here), is there an "easy" way to tell which resistor value is tied to it without trying all the combinations? Ebay sellers seem to say no keys included. I *think* I have confirmed that my resistors are correct and the wiring to the BCM is intact, so I am starting to think the BCM is bad. I am going to test that circuit again and if I find out otherwise I'll edit this post.
Details for what I did for all the other searchers who may stumble across my same problem. I did manually ground the yellow/black wire in the front fuse box connected to the starter relay and the car was then able to crank regardless of VATS/Security light. As mentioned, since I have my tune set for VATS disabled, the tune allowed the computer to let the car run regardless of the VATS signal from the BCM. Back on the road!!
This now makes VATS unable to strand me ever again. My security light is now blinking instead of solid since I was farting with the resistors/wiring, but it annoyed me enough to pull the gauge cluster out (easy) and put electrical tape over the annoying blinking security light until I either get a new BCM or will retest/adjust/calibrate my underdash resistors and get rid of the ugly/hacky tape. I plan on leaving the ground in place on the starter relay forever so I'm never stranded regardless.
Thank you for the detailed information, especially about the blinking versus solid light, I was unable to find that information. Very helpful!!!
Thank you for all the information, I have an update and one more question if you don't mind.
Question: If I buy a BCM from Ebay (or someone here), is there an "easy" way to tell which resistor value is tied to it without trying all the combinations? Ebay sellers seem to say no keys included. I *think* I have confirmed that my resistors are correct and the wiring to the BCM is intact, so I am starting to think the BCM is bad. I am going to test that circuit again and if I find out otherwise I'll edit this post.
Details for what I did for all the other searchers who may stumble across my same problem. I did manually ground the yellow/black wire in the front fuse box connected to the starter relay and the car was then able to crank regardless of VATS/Security light. As mentioned, since I have my tune set for VATS disabled, the tune allowed the computer to let the car run regardless of the VATS signal from the BCM. Back on the road!!
This now makes VATS unable to strand me ever again. My security light is now blinking instead of solid since I was farting with the resistors/wiring, but it annoyed me enough to pull the gauge cluster out (easy) and put electrical tape over the annoying blinking security light until I either get a new BCM or will retest/adjust/calibrate my underdash resistors and get rid of the ugly/hacky tape. I plan on leaving the ground in place on the starter relay forever so I'm never stranded regardless.
Thank you for the detailed information, especially about the blinking versus solid light, I was unable to find that information. Very helpful!!!
Last edited by mk3cn4; 06-11-2021 at 09:55 AM.
06-12-2021, 01:05 PM
#5
Unfortunately no, there really isn't an easy way to determine what resistance value a used BCM was originally matched to. There is no code or measurement you can check to determine that value. A brand new BCM will match itself automatically to the first key used to start the car after installation. After that, the BCM is no longer programmable so you can't change the matched resistance value once the first key has been used.
The easiest way is to get one of the BCM bypass kits that include a box containing all possible values and either a dial or a set of DIP switches to allow selection of each resistance value without the hassle of wiring individual resistors until you find the right ones. They are plug-and-play so you just plug it in and cycle through the dial or DIP switches until you find the setting that lets the car start (or in your case, turns off the security light). The whole process can be done in less than 10 minutes. The best one I know of is the Gator VATS Bypass Module (their part number VBM054). It is available online for about $36 from the manufacturer, Gator Tools. Watch out that you don't get one of the VATS Bypass kits that actually bypass the missing fuel enable signal rather than the key resistance - they're much more expensive and you already have the PCM programmed to ignore the missing fuel enable signal. And, whatever you do, DO NOT buy the rip-off kit for $259 from New Rockies... all they do is combine a key bypass and signal bypass into one module then charge three times what it's worth.
Other than that, you can buy all possible combinations of resistors and do it yourself... much cheaper since resistors cost mere pennies each but much more of a pain in the butt for installation.
The easiest way is to get one of the BCM bypass kits that include a box containing all possible values and either a dial or a set of DIP switches to allow selection of each resistance value without the hassle of wiring individual resistors until you find the right ones. They are plug-and-play so you just plug it in and cycle through the dial or DIP switches until you find the setting that lets the car start (or in your case, turns off the security light). The whole process can be done in less than 10 minutes. The best one I know of is the Gator VATS Bypass Module (their part number VBM054). It is available online for about $36 from the manufacturer, Gator Tools. Watch out that you don't get one of the VATS Bypass kits that actually bypass the missing fuel enable signal rather than the key resistance - they're much more expensive and you already have the PCM programmed to ignore the missing fuel enable signal. And, whatever you do, DO NOT buy the rip-off kit for $259 from New Rockies... all they do is combine a key bypass and signal bypass into one module then charge three times what it's worth.
Other than that, you can buy all possible combinations of resistors and do it yourself... much cheaper since resistors cost mere pennies each but much more of a pain in the butt for installation.
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mk3cn4 (07-23-2021)