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All wiring for ecm gone what will happen to vats system now?

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All wiring for ecm gone what will happen to vats system now?

Old 06-28-2011, 04:06 PM
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All wiring for ecm gone what will happen to vats system now?

I am sure this has been discussed in previous threads, but nothing came up for me help wanted if possible. Some info is a 1992 rs.
I am doing an engine swap from a tbi 350 to carberated. I rebuilt an older motor got all the new goodies including a msd street fire distributor. My question is I have taken all the wiring from the ecm out and no ecm anymore is the vats system going to give me problems with starting the car?
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Old 06-29-2011, 01:14 AM
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Welcome aboard thirdgen.org.

Yes, the ECM is an integral part of the VATS system. You will have to bypass it now. That isn't a big deal, mainly hooking the start wire directly from the ignition/neutral safety switch to the start solenoid.

There are a couple of tech articles on VATS linked from the thirdgen.org homepage you might want to take a look at.
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Old 06-29-2011, 09:29 AM
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Re: All wiring for ecm gone what will happen to vats system now?

I forgot I tooked mine out. Went to fire up my car and nothing. Looked under the dash and no ecm oops theres the problem lol
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Old 06-29-2011, 08:43 PM
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Re: All wiring for ecm gone what will happen to vats system now?

No - you won't have any VATS issues. VATS only controls two things ... 1) it sends a signal to the ECM to fire the injectors (no injectors means no problems), and 2) it controls the starter enable relay (which is in no way wired into the ECM.

So, you should start and ruin just fine without ECM (I haven't had one for 5 years and no issues in my carbed car).
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Old 06-30-2011, 02:12 PM
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Did I get this wrong again?

https://www.thirdgen.org/vats_passkey_system

I thought that without the ECM to tell VATS it's okay to start the car, the start power won't get from the ignition switch to the starter solenoid. I'm probably wrong.

This is where I will shut up, as I've never owned a VATS car.
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Old 09-04-2011, 07:52 PM
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Re: All wiring for ecm gone what will happen to vats system now?

i have an 89 trans am gta with the vats system....i would like to replace the lock cylinder and box...do i have to get a new box and locke cylinder with the key or can i just use a new lock cylinder and key with the old box???? please help!!!
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Old 09-06-2011, 04:54 PM
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Re: All wiring for ecm gone what will happen to vats system now?

vats does control the ground side of the start enable relay, easily bypassed though.
no start enable relay ground = no power to starter solenoid.

the vats box is tuned to the resistance of your key chip. if you replace the key, you need to make sure you get one with the same resistance level (theres 15 different ones) or you wont be able to start your car unless you bypass the VATS system.
you can also take your new lock cylinder with your old key to a locksmith and they can rekey the new lock cylinder to work with the old key.
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Old 09-06-2011, 09:10 PM
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Re: All wiring for ecm gone what will happen to vats system now?

alright i was able to get it to crank over..it turns out the previous owner bypassed the vats system by wiring in a resistor and changed the lock cylinder to a non vats lock cylinder but in that wiring harness i found some melted wires(had nothing to do with vats) so i replaced the wiring harness from buying one off of ebay and came with a new pass key box so i just used that one, not knowing that each box is different i tried to start the car but nothing happened i soon relized that i needed to use the old vats box so i hooked it up and now the car cranks and has fuel injection
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Old 09-06-2011, 09:33 PM
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Re: All wiring for ecm gone what will happen to vats system now?

all i did was jump a wire before the vats box to after the vats box and walla it started
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Old 12-05-2018, 03:45 PM
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Re: All wiring for ecm gone what will happen to vats system now?

Don't want to pull a really old post back alive but the information is wrong here. The Passkey/VATS module is independent of the ECU in a thirdgen. The module is grounded through the C207 connector beside the ECU so as long as you take that wire and ground it the module will work and still control the starter relay without the ECU. The Security light will cycle with the key, and the starter will disable if it doesn't detect the resistor in the key. The VATS module sends a signal to the ECU and provides a ground to the starter relay only, the ECU doesn't communicate to the VATS module. I know this from personal experience as this is how my car is currently set up (well except not carbed but I don't have a factory ECM)

With that said completely removing it is the safest solution in this situation --
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