stezhead54

So i have an 89 with a working vat's key and module. I'm in the process of converting the motor to an lt1, and i was wondering if anyone can tell me if the vat's module that is currently in the car will work with the pcm. I'm kind of hoping that it will so that i won't have to get the pcm re-programmed or get a vat's delete or bypass module. I've searched around and all i can find is people trying to get rid of it or bypass it. Haven't found anyone who's actually used a good one on the lt1 swap.

1991sleeper

iTrader: (-3)

Just bypass it ... Remove the module behind the driver side kick panel and splice the two wires

stezhead54

The thing is that it works though. and i want to keep the functionality of it if i can.

alex722607

iTrader: (3)

Rare is a person such as yourself that wants to keep vats. I should know I am the same way!

All you have to do to keep vats is this, remove the pins at the ECM that come from the vats module. I think it's just fuel input but I could be wrong. Next insert that pin into the connector for the PCM and it will work fine as long as it is the right cavity. It should be either a purple wire or dark blue. I believe that until 1996 lt1 cars used a vats module like ours and in 97 they switched to a body control module which still sent the same wire to the PCM (essentially the bcm was a bunch of modules in one) the same signal is sent no matter if you have a 1989 or a 2002. The only thing that changed was the length of the key I believe.

Pocket

iTrader: (24)

^ You're close. OBDI LT1s used a module like ours for 92-95

The PCM is still going to need a tune unless you take absolutely everything from the donor car. Not worth it

The 3rd gen VATS is still active to an extent. It only controls the starter enable relay. Fueling isnt protected anymore. This saves you from any goober with a screwdriver, but the more common theft method of flatbed conquers all antitheft systems

stezhead54

So for the vats to work properly i would have to have either the vat's from the 94 car that i got the computer from, or from a car from 92 to 95? My 89 is going to be different? I've got the wires from the vat's hooked up to the pcm already, and the security light comes on and goes off as it should, but the car only starts for a second or two and then shuts off. So i'm kind of thinking that i need a different vats module, but i could just have it wired up wrong :-P

As for everything from the donor car...there shouldn't be much if anything from a 94 that i would need to take with me. I've got the transmission already. The only thing i can think of that i would need would be the digital dash from a 91-92 camaro, so i can have a speedo. I've already gone over all of the wiring diagrams from both cars, and picked out everything that crosses over, and everything that doesn't matter to the running of the car, ie traction control sensors and abs sensors and such. yes i know i'm going to have the check engine light, but i'm going to be moving here in a month or so and i'd really like to be able to drive the car to my new house instead of having to have it towed there.

Pocket

iTrader: (24)

Find a diagram and integrate it into your car

alex722607

iTrader: (3)

The wire that you plugged into the pcm from the vats module, make sure it is in the right cavity or fuel will get shut off at the injectors. Is the pcm throwing any codes, you could be chasing the wrong problem.
You are able to crank so that means that the key is okay as is the connection from the ignition switch to the vats module. If you changed the ignition, or got a different key (with a different resistance value) or got a different VATS box, then you would have a problem. All those things need to be from the same car for the system to work properly.

stezhead54

So i have answered my question. The vats module for my car 89 camaro rs uses a 30 hz signal to the ecm. The 94 pcm uses a 50 hz signal. So the answer is....no i can't use the vats module in my car. Now i can do one of three things.....either find a key, cylinder and module from a car that puts out a 50hz signal, do the bypass, or get the ecm reprogrammed. Here's the website that i found the information on.

http://www.bakerelectronix.com/vats_faq/

Decisions decisions. Guess i gotta figure something out :-P

alex722607

iTrader: (3)

That can't be. I have both a 2002 bcm in my car and the original vats. I have the bcm bypassed and stock vats operational. I can take the fuel output wire from either and plug it into my ECM and anti theft will not turn on ( or rather injectors won't turn off)

The disclaimer on that page says it may contain errors. As for 50 he I don't know where you got that from, but 88-02s had the same signal from the vats system to the computer.

Chances are you might have plugged it in wrong or you could have fried something.

stezhead54

The reason that you are able to switch between the two modules is because they both put out the same frequency. It seems like if i had a vats from after 93 i would probably be ok. Also if you want there are a few places that say there are two frequencys. here's one of the threads i found.

https://www.thirdgen.org/forums/elec...-question.html

i very much doubt i've fried anything. the car starts and then dies quite quickly. The normal time that it takes for the computer to verify that the correct key is in the ignition. I'm thinking i might just have to break down and get the pcm reprogrammed.