Decat

So I had problems with my Vats not allowing startup just like many of us. So I took the ECU out and had PCMforLESS tune it for the new mods and turn all Vats off. I got it back and everything seemed to be fine for the first few weeks, and then it started randomly not starting again because of the steady on security light. Called PCMforLESS and they confirmed that all Vats is turned off on my ECU now, he said that it might be a bad ground now?

It rained a lot here yesterday in Houston, and now the Vette will not start due to the steady on Security light from Vats. Can someone please provide a link to the ground points so I can eliminate that as a potential cause for this problem? Also any other ideas would be appreciated. I thought turning off the Vats would fix this problem, I cannot believe I am still having problems with this.

antfarmer2

Try your other key and look at the ground in front of the driver door under the carpet. also try unlocking your door with the key

AGENT 86

Not sure on your 94, but my 86 security light has nothing to do with VATS, just the forced entry alarm.

Decat

If the security light is steady on Vats has taken over and will not let the engine start. This is what is happening to my Vetter about 50% of the time. Having the PCM reprogrammed to ignore Vats I am very confused as to why I am still not able to start the car. As of now the Vette is stranding on my driveway until I hear some useful info here.

So the ground under the driver's carpet? Do I need to remove the seat? Is it on the firewall or under where your feet are or on the side where the speaker is? Where are the other potential grounds? This is really frustrating I thought having the PCM reprogrammed would get rid of this problem.

Tom400CFI

Because the majority of "VATS" is in the BCM, not the ECM. If your key's resistance isn't getting to the BCM due to contacts or wires in the tumbler, then the car won't crank. It may run if you roll start it though.

Diagnose the actual problem and fix it. I'd start my checking my resistance though the key, at the two pin connector at the bottom of the column. Should be a purple wire w/a white trace (IIRC) and maybe a black wire? Been a while.

Hooked on Vettes

You need to enable the Starter Theft Deterrent relay.
It's located under the driver side dash.
Remove the carpeted panel you will then see a metal panel which needs to be removed.

Along the front edge of the dash will be a bunch or relays.
The starter enable relay will have a the following wires at the relay socket. Large gauge Yellow wire a Large gauge Purple wire, small gauge Yellow wire and a small gauge Yellow/Black wire.

You need to ground the small gauge Yellow/Black wire.
This will manually enable the starter relay. Normally the CCM grounds this wire.

If after grounding the Yellow/Black wire the starter doesn't engage
the relay could be bad so swap it with another one. All the relays in that area are all the same.

Decat

Thanks so much HookedOnVettes, I have actually taken that out to look at it before, but never knew what to do with it. I will try this tomorrow, thanks so much!

Decat

Alright I took the yellow and black wire out of the relay connector and ran it straight to a nut on the metal bracket on the steering column, then I reinstalled the really into the harness without the yellow and black wire attached. Is that correct or do I need to just splice into the yellow and black wire and then run that spliced wire to a ground?

I will try splicing in later tonight because removing the yellow black wire and grounding it did not work, or I need to get another relay?

Decat

That fixed it. Just spliced into that Yellow/Black wire and ran the spliced wire to a nut on the steering column mount.

THANK YOU!!!!!

Tom400CFI

That likely means that your CCM isn't reading your key. Why don't you fix that?

Decat

Because a "fix" still doesn't guarantee that I don't get stranded by the problematic, inconsistent and sensitive Vats. This over rides the Vats so I don't have to worry about to troublesome Vats system again. I have had all kinds of problems with the Vats ever since I got the C4, I am so happy to have that problem fixed.

antfarmer2

Good job

Tom400CFI

Interesting. My car has over 150k miles and I've never had a problem with it. I certainly wouldn't call it problematic, inconsistent and sensitive troublesome ....but that's just me, I guess.

WW7

Consider yourself lucky Tom...There are 3 other guys with C4s that I get together with once in awhile, and all 3 have had Vats issues... I had such a problem with mine that I eliminated the vats completely from my car.....Once you have been left stranded a few times, you may get a completely different opinion about Vats.....WW

ssv1761982

Will this 'fix' work on an '86 too? Mine is unpredictable.

antfarmer2

Have you tried a new key worked for me.

1bdvet

I think we all had this problem, I herd people say take eraser to the pellet, cleans it and makes for better contact.
What I finally did was replace the ignitions switch, there seems while back they had TSB for that, and not recall.
Once I had it done 20 years ago I never had problem with it, or the person that has my C4 has never complained of starting problem.

antfarmer2

that was a good quik fix but did not last.

1bdvet

When I had the dealership replace ignition cylinder decades backn bever had the problem again, and the person I sold the car to 6 years ago hasn't any problems.
I guess I was lucky, what can I tell you.