formula1LE

iTrader: (3)

Okay, a little background first. I bought a (supposedly) running 89 TA with a TPI motor that I wanted for the drivetrain. I got the ignition key with it but it turned out to be the wrong key-it wouldn't even turn the cylinder and the previous owner did not have the correct key. So I wanted to verify the running condition of this motor prior to ever installing it in any other car. I spent the last two days researching various posts about the VATS and here's how I bypassed it. Thanks goes to this board and to a useful utube video from a guy who showed how on a different type of GM car. First you need a multimeter. Next, go to any stereo shop or Radio Shack and ask them for a pack of GM VATS bypass resistors-they come 15 to a pack and you should not pay more than about $2 for them. The pack shows the ranges of values for each given band of color but it really isn't important-you'll see why in a minute. Now, if you have your key, it is real easy-I had no key so I had to do some take the ignition switch off the column down low. If you remove the lower dash cover under the column you will see an orange sleeve with two white wires in it-trace it until you come to the connector that it plugs into-dis-connect it. Set your multimeter to 20K ohms and probe both ends coming from the ECM-not from the column side. This value should be the same (or very close) to the value on your key if you were to probe both sides of the resistor pellet on your ign. key. My friends Firebird read .680 on his key. Basically what this says is that the computer has a set value it wants to see from the key +/- 5% variance. So, in my case I had no actual key so i just probed the two white wires from the ECM side and my value was 5.640....so I just looked up the values on the sheet that comes with the GM resistor pack and add three of them to get me to a total of 5.625-that was the closest I could get. I probed the ends of the 15 resistors until I got to the three that I needed to add up to the total resistance required-this was easier than trying to see the little color bands for the values! I twisted them in a chain and twisted each each to the two white wires under the dash from the ECM. I turned the ignition switch by hand (I had no key, remember?) and the engine started. Now, there are some interesting observations I made while going through this whole process-I had some issues along the way which I fixed easily but they may help somebody troubleshoot their VATS system should they have an issue some day. You know if the resistance is wrong because when you turn the key to IGN on, the security light will come on and it should go off within three seconds-if it stays on, it (usually) means the ECM is not seeing the correct range of resistance. There is a relay behind the drivers kick panel that triggers the ECM's ability to see it....if you have the right resistance, and you dis-connect that relay, the car will crank, but not fire and the security light will go off. If you do not have the right resistance and that relay is dis-connected, the car will not crank and the security light will stay on. So that relay is very important. I suggest buying a few extra and keeping one with you at all times. The GM part number is #14093107. Now, this car had all of it's interior stripped out so when I attempted to start it with the correct resistance tied in and a good relay, it cranked but did not start-the fuel pump wouldn't come on. I discovered that within the wire loom for it there is a black 14 gauge ground wire right next to the drivers seat up front where the fuel pump itself gets grounded to-it was dis-connected. I secured it to ground and the car fired right up and idled. The actual control module for the VATS is under the passenger side of the dash mounted on a bracket right in front of the ECM. It slides right out and you can flip it open to view the entire resistor board-pretty cool really. So, all this was learned in an attempt to make sure this TPI motor was indeed a good one and it was-all in a car which had the VATS and I had no key for it. All, in all, there are a lot of ways to modify this system and looking at it once I was through, I can see how somebody with knowledge of this could use it to steal these cars so I advise studying the system and finding ways to add to the complexity of it to keep your car safe. This was fun and now I can add this whole motor/tranny/ECM kit to my 4x4 truck I'm building! Hope this helps you guys!

one92rs

iTrader: (5)

hit tech articles in my sig.

formula1LE

iTrader: (3)

That was good reading....the other relays work in concert with the VATS too though-you know you always have the right resistance if you probe coming from the ECM-not the column. If you have the right key to begin with, it's much easier-I did not have that luxury
I was told any mobile key service can make an ignition key for you-if this is the case, then if they know how to bypass the VATS, that makes for a good opportunity for a thief...beware, I see the posts about stolen GN's and TTA's all the time it seems-do the GN's have VATS? I can't recall. Anyway, it's a good system imo if it's understood and, easy to modify.

3rd-gen's 4life

I have a question about my key I have im getting a reading of 375 which is too low my range is 386-438 with the sweet spot being 402. Now if I still get the same reading 375 that is reading to low by the wire under the column...then what does that mean? and this might be a dumb question but do I loss resistance with a worn down pellet I can't feel the metal edge of the pellet eye with my finger so its worn pretty low!!! or do I simply need a new key? thanks for any help!!!!!