VATS & PCM programming


Well-Known Member
Hi folks

I have a question to those of you who program PCMs.

I suspect that I may have a VATS issue. I'm doing an LS swap. The donor was a 2003 Silverado 6.0L. Before I pulled the engine I ran the truck and disconnected the BCM to disable the VATS. When the engine was out I successfully started and ran the engine several times with no issues. I installed the engine into a Jeep and it ran fine the several times I started it.

Yesterday I was playing around with it in the driveway and shut it off while I had dinner. When I returned I tried to start it. It would fire very briefly while "on starter" but not run. I actually held the starter on to see if it would continue to run, it did not.

I have experienced VATS activated before on my '99 Jimmy, but the engine would actually run about 2-3 seconds after releasing the starter.

Now I've gone though all my wiring and confirmed constant power and ground to the PCM at all times. Fuel pressure is constant at all times.

My question, is it possible that the VATS has somehow reactivated itself?

The relearn procedure is for the BCM, am I correct? This of course has no BCM.

VATS can be deactivated in the PCM through a tune. It may be looking for the signal from.the BCM to allow the start. But if it was VATS it shouldn't even crank.


Well-Known Member
When the VATS was activated on my '99 Jimmy it would crank and start but dies in 2-3 seconds. This cranks and fires but dies before I release the key.

I planned on deleting the VATS among other things, but I wanted to get it driveable first so I could complete the swap, THEN get it tuned.

At this point I may just get a mail order tune, 100 bucks including shipping.
The way it works (crank/no crank) could be model or year dependent. I know that on our platform, I6 or V8, the starter, fuel and spark are disabled. Saw that each time I had to do a security relearn with different PCM's.

Even if just tuning a stock vehicle, VATS should be disabled because it always seems to rear its ugly head when you're alone on a desolated dirt road in the middle of the night with no cell coverage.


Well-Known Member
Well I've got my LS Jeep, and my Envoy, so yes, 2 for sure.

Now I can sell my Superchips hand held tuner for my Envoy and retune it with HPTuner.