VATS Issue/Question
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Launching!
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From: Palm Harbor, Florida
VATS Issue/Question Hey guys, so I am having some issues that I believe relate to the VATS, wanted to get some input from the electrical side of the forum, but first, some background. I just pulled my motor from the bottom and did new cam & valve-train, stall, and other little things. I put it back together and it wouldnt start, problem with a slow crank so I created the post here https://ls1tech.com/forums/lt1-lt4-m...ank-video.html. After I replaced the battery cables, it cranked better, but after several tries it all the sudden stopped cranking completely. The security light is now flashing and didnt change when trying three different keys. I measured the resistance of each of those 3 keys and they were all at .73. I tried to measure the resistance in the connector under the steering column to see if the same resistance was at the key lock cylinder, but could not get any reading on it. (trying to do step 2 here http://shbox.com/1/vats_bypass.jpg)
I have done many searches on VATS because obviously there are a million posts on it, but I tend to only find info on doing the bypass. I cant figure out exactly how to troubleshoot this issue. During the rebuild I got a mail order tune and had the VATS removed, so I guess I don’t exactly understand how that impacts this if I am still having issues. Any thoughts from you guys?
I have done many searches on VATS because obviously there are a million posts on it, but I tend to only find info on doing the bypass. I cant figure out exactly how to troubleshoot this issue. During the rebuild I got a mail order tune and had the VATS removed, so I guess I don’t exactly understand how that impacts this if I am still having issues. Any thoughts from you guys?
Joined: Nov 2003
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From: Jacksonville, FL (originally from Toronto Canada)
The SECURITY light will do one of two things if there is a VATS problem. If the resistance of the key it sees is incorrect, the light will be solidly lit. If it can't see a resistor at all, the light will flash. That was intended to prevent the use of key blanks that didn't have resistors or a key where the resistor was physically broken. In this case it probably means that you have an open circuit - a break in one or both of the wires between the ignition cylinder and the BCM.
Start by unplugging the connector at the base of the column, insert your key in the ignition and measure the resistance between the two pins in the connector. If you get no reading (infinite resistance) then the problem is in the column... probably the ignition cylinder itself. If you do get a valid reading then the problem is somewhere in the wires between the base of the column and the BCM.
You need to select a lower range on your ohmmeter. The allowable resistance values range from 402 through 11,800. The one you are probably seeing is #13 (7,500 ohms) but your range is too high so it appears as a decimal.
Start by unplugging the connector at the base of the column, insert your key in the ignition and measure the resistance between the two pins in the connector. If you get no reading (infinite resistance) then the problem is in the column... probably the ignition cylinder itself. If you do get a valid reading then the problem is somewhere in the wires between the base of the column and the BCM.
You need to select a lower range on your ohmmeter. The allowable resistance values range from 402 through 11,800. The one you are probably seeing is #13 (7,500 ohms) but your range is too high so it appears as a decimal.
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Launching!
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Thanks for the response WhiteBird.
Mine is definitely flashing, so it must be no resistance at all.
Ok so I have done this (several times actually because I was questioning myself) and I get no reading, so it must be related to the ignition cylinder. So my question would be does doing the VATS bypass and wiring in a resistor that matches my key solve this issue or will I need to replace the ignition cylinder?
I actually followed this video and have the same cheap multimeter on the same settings. Forgive me as I stumble through this as electrical issues can confuse me very quickly! 
The SECURITY light will do one of two things if there is a VATS problem. If the resistance of the key it sees is incorrect, the light will be solidly lit. If it can't see a resistor at all, the light will flash. That was intended to prevent the use of key blanks that didn't have resistors or a key where the resistor was physically broken. In this case it probably means that you have an open circuit - a break in one or both of the wires between the ignition cylinder and the BCM.
Start by unplugging the connector at the base of the column, insert your key in the ignition and measure the resistance between the two pins in the connector. If you get no reading (infinite resistance) then the problem is in the column... probably the ignition cylinder itself. If you do get a valid reading then the problem is somewhere in the wires between the base of the column and the BCM.
Joined: Nov 2003
Posts: 11,328
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From: Jacksonville, FL (originally from Toronto Canada)
Yes, you can do a VATS bypass and it will eliminate the broken connection at the ignition cylinder so you don't have to replace it. Buy yourself a single 7500 ohm resistor at your local Radio Shack (if you still have one around) or online for a few cents each (ebay currently has an 8-pack for $3.70). Unplug the connector at the base of the steering column and insert one leg of the resistor in each side of the connector going into the car (towards the BCM not towards the column). If that solves the starting problem then fix it up so that the connection won't come apart and nothing is exposed to short out.
You're lucky because #13 7500 ohm is the only VATS resistance that can be created with a single resistor. All the others require a combination of resistors in series or parallel.
You're lucky because #13 7500 ohm is the only VATS resistance that can be created with a single resistor. All the others require a combination of resistors in series or parallel.
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Launching!
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From: Palm Harbor, Florida
Yes, you can do a VATS bypass and it will eliminate the broken connection at the ignition cylinder so you don't have to replace it. Buy yourself a single 7500 ohm resistor at your local Radio Shack (if you still have one around) or online for a few cents each (ebay currently has an 8-pack for $3.70). Unplug the connector at the base of the steering column and insert one leg of the resistor in each side of the connector going into the car (towards the BCM not towards the column). If that solves the starting problem then fix it up so that the connection won't come apart and nothing is exposed to short out.
You're lucky because #13 7500 ohm is the only VATS resistance that can be created with a single resistor. All the others require a combination of resistors in series or parallel.
You're lucky because #13 7500 ohm is the only VATS resistance that can be created with a single resistor. All the others require a combination of resistors in series or parallel.
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Launching!
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Ok, so I bought some resistors and tried to hook it up today . . . but didnt have any luck. The RadioShack didnt have a 7500 ohm resistor so I bought a 5 pack of 3900 ohm and a 5 pack of 1500 ohm. I tried to hook them up in a number of different combinations but it didnt work. Sometimes the security light would flash, other times it would be lit solid. Also, I dont know if I am doing it wrong or is my cheap multimeter is acting up, but when I measure the resistance in my key it will be .72, and I check all 3 and it is consistent. Then later I will check it again and it will be .68 or .69 on all 3 keys. then later it will be back to .72 . . . I just dont get it!
Last edited by derekstl; Sep 19, 2016 at 11:00 PM.
Joined: Nov 2003
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From: Jacksonville, FL (originally from Toronto Canada)
There is no reasonable combination of 3900 ohm and 1500 ohm resistors that will total 7500 ohms. You could put all five 1500 ohm resistors in series (end to end) but that makes for a long string of resistors with multiple connection points to potentially fail. You should try another electronics store if there is one near you or order the correct resistor online. 7500 ohms is one of the standard resistor values.
Here are the possible resistors values for VATS:
1 - 402 Ω (not used in 98-02 F-bodies)
2 - 523 Ω
3 - 681 Ω
4 - 887 Ω
5 - 1130 Ω
6 - 1470 Ω
7 - 1870 Ω
8 - 2370 Ω
9 - 3010 Ω
10 - 3740 Ω
11 - 4750 Ω
12 - 6040 Ω
13 - 7500 Ω
14 - 9530 Ω
15 - 11800 Ω
If you don't get consistent readings when measuring the resistance in the key pellet then either your meter is no good or you're not getting good contact between the probes and the contacts on the pellet. The resistance of the pellet will not change so you should be able to get the same reading every time. Try using some rubbing alcohol to thoroughly clean the contacts of accumulated grime before measuring.
Here are the possible resistors values for VATS:
1 - 402 Ω (not used in 98-02 F-bodies)
2 - 523 Ω
3 - 681 Ω
4 - 887 Ω
5 - 1130 Ω
6 - 1470 Ω
7 - 1870 Ω
8 - 2370 Ω
9 - 3010 Ω
10 - 3740 Ω
11 - 4750 Ω
12 - 6040 Ω
13 - 7500 Ω
14 - 9530 Ω
15 - 11800 Ω
If you don't get consistent readings when measuring the resistance in the key pellet then either your meter is no good or you're not getting good contact between the probes and the contacts on the pellet. The resistance of the pellet will not change so you should be able to get the same reading every time. Try using some rubbing alcohol to thoroughly clean the contacts of accumulated grime before measuring.
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Thread Starter
Launching!
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From: Palm Harbor, Florida
I did try to put all 5 1500 ohms together and that didnt work. When the keys were reading 6.9 I was putting two 1500 & 1 3900 together and no luck. RadioShack didnt carry the 7500 at all, not even in a variety pack. I went ahead and ordered some from Amazon with same day delivery (thats so crazy they can pump it out that fast) and it cost me $10 total for a 25 pack. I will give it another shot tonight, I will also try to clean the keys and get a better reading.
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Verdad Gallardo Joined: Nov 2003
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From: Jacksonville, FL (originally from Toronto Canada)
You would have to put all five 1500 ohm resistors in series (end to end) and ensure near perfect connections between them to get 7500 ohms. If you put all five side by side so that they all share just one connection at each end (parallel) then the total resistance will be only 250 ohms which would not work.
Thread Starter
Launching!
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Ok, so I was messing with this again last night, the 7500 ohm resistor still did not work. I cleaned the keys and tried to measure them again, I got .69 consistently. After a while, I started to realize . . . I think it was reading the voltmeter incorrectly. The value I got was .69 and had the same settings as the video I posted earlier. He said on the video that was in thousandths, so move the decimal 3 places . . . that would be 690 which would better match value 3 not value 13. I was originally getting a value of .72 and when I posted it I was told it matched value 13 and just blindly followed it because these stupid voltmeters confuse the h*ll out of me! (Totally not your fault WhiteBird, I really appreciate your help!)
So now I think that I am going to get some resistors that will give me 690 ohms and see if that is the magical solution.
So now I think that I am going to get some resistors that will give me 690 ohms and see if that is the magical solution.
Joined: Nov 2003
Posts: 11,328
Likes: 346
From: Jacksonville, FL (originally from Toronto Canada)
There is no 681Ω resistor available as a standard value but there is a 680Ω which is close enough. Or you could use a 680Ω with a 1Ω in series to make an exact match.
Other options are using a 2700Ω in parallel with a 910Ω to give 680.6 ohms or a 7500Ω in parallel with a 750Ω to give 681.8 ohms.
Switch your meter to the 2000 range (instead of 20K) so that you can get a more precise reading of the key pellet.
Other options are using a 2700Ω in parallel with a 910Ω to give 680.6 ohms or a 7500Ω in parallel with a 750Ω to give 681.8 ohms.
Switch your meter to the 2000 range (instead of 20K) so that you can get a more precise reading of the key pellet.
Thread Starter
Launching!
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From: Palm Harbor, Florida
Ok so I bought more resistors and plugged in a 680 ohm and it worked perfectly! Definitely fixed the issue for me. Thanks again WhiteBird for your patience and help!!
Unfortunately the car still didn't start, but it at least is turning over now. I have an issue with it cranking slow in this post https://ls1tech.com/forums/lt1-lt4-m...ank-video.html
Unfortunately the car still didn't start, but it at least is turning over now. I have an issue with it cranking slow in this post https://ls1tech.com/forums/lt1-lt4-m...ank-video.html
This post my save my weekend. I have been having a no start issue, but without security lights. I tested my key tonight and its 680 as well. I will try to round up some resistors and cross my fingers.
Thanks
Thanks