So, I was checking under my vehicle for loose or damaged wiring that would lead to a CEL code I've been getting and thusfar haven't found anything. Thought I'd take a look at the PCM and see if I noticed anything there.

My drivetrain is out of a 98' F-body (I believe it was a Trans Am, but am unsure). I had a spare LS1 PCM lying around from what I believe is a 98' F-body. I replaced the PCM with my extra unit, but the car would only crank and not start.

I was guessing that the extra PCM hasn't had the VATS removed yet, and I did have an error for the EVAP system pending based on the ALDL port. The car cranks, fires, then immediately dies. Nothing you can do to change it.

So - I need to know what's necessary to swap the one PCM to the other? The engine/transmission is obviously a swap, so would I simply need to provide a VIN from a 98 F-body and have the computer flashed to remove the VATS, EVAP, and rear O2 sensors?

It's a stock LS1 swap (AFAIK) and should only need to be run to stock specs.

Tell me what YOU'D do.

 

Thats the main symptom of VATS

What code is the old PCM throwing?

 

The PCM is giving code P0785 (3-2 Shift Solenoid Malfunction). I've been in the pan, replaced the solenoids but the code persisted. Leading me wiring or PCM. Since the PCM is easily accessible, I thought I'd test that theory, but wiring might prove cheaper, just more time consuming with more hours under the vehicle.

Thanks for the idea on the VATS, I imagine with it disabled I'd be in business...and running right if I had the other items mentioned disabled as well. Now to find somewhere that can do it cheap.

 

You can build a vats module for about $25 in radioshack parts. Of course there will be a bunch of other codes thrown, but it'll get you running and you can filter out the other junk to see if the trans code comes back

http://temp.corvetteforum.net/c3/70lt1/vats.shtml

Had to build one last night for an emergency test

 

That's what I did and works great.

 

Alright guys, I got the spare computer to run the car (long story though).

So, after all was said and done, I received some codes I expected.

EVAP system voltage
(several codes set)
Rear O2 Sensor errors
3+

Cylinder 1 Misfire

But I was really surprised by my transmission codes. P0753 and P0758 (Shift Solenoid A and Shift Solenoid B / Electrical). I drove the car up, down, and around the block. I was very happy that the original P0785 code wasn't displayed, but was unsure if the two codes shown above are related to the other codes and the car being in limp home mode...or is this a separate issue altogether?

------------
edit
------------

So I tested the car again, still got the P0753 Shift Solenoid A code, but never got the P0758 Shift Solenoid B code...pulled back into the driveway, and cleared the codes and they didn't return...but most importantly (at least to me) the P0785 3-2 Shift Solenoid malfunction code didn't illuminate. I'm leaning towards a bad PCM causing my issues.

I'm almost certain my LS1/4L60e are nearly stock. I did notice quite a bit of stumbling though with the other PCM, and a massive hesitation/bogging when coming off idle...actually makes the car shake. I was getting the cylinder 1 misfire code still, which is what I'm attributing the shaking/vibrations from...and my LS1 is not running dual cats, nor rear O2's like a stock vehicle...plus the EVAP systems are removed.

Can anyone tell me if those items would cause the driveability issues that I'm experiencing?