Replacing the PCM (F-body)...

[joecar]

I installed a PCM, and I did these steps to get car running (require steps 1-3 minimum to run):

1. do full flash to PCM;
2. write VIN to PCM using scantool;
3. VATS relink PCM to BCM using tunetool;
4. make sure engine starts and runs properly;
5. do CASE relearn;
6. write oil remaining life to PCM using scantool;

Are there any other things that need to be done...?

What about BCC...?

Further question: does VATS relink write the BCM's serial number (or something) into the PCM (how does it work)...?

[voda1]

Can all that be done with commercial license?

[joecar]

Yes.

[zapp168]

Joe I think that is all, I have done two cars and they have not come back after the fact. The first car I tried however, I copied the file from the old computer and when I flashed into the new one the VIN went all zero's and set off the air bag light.

[JAY4SPEED]

Further question:
Does VAT relink write the BCM's serial number (or something) into the PCM (how does it work)...?

In a way it does. As I understand it, the VAT relearn "introduces" the PCM to the BCM via the class 2 data circuit. They would have to exchange some specific "unique" identifying data that ties that specific ECM to that specific BCM. I'm not sure how that is accomplished but it would have to be a serial number or unique controller id. It could be possible that the "fuel enable" code needs to be established between the two modules. For example, if you created a password to log into windows on your computer, you would have to create the password and also tell the computer what password to expect so that your both on the same page. Same thing happens between the ECM and BCM. Some other critical modules accomplish this by learning the VIN from the BCM IE: the SDM (airbag module).

How it works in a nutshell:
In the Fbody example you posted, the Fbody uses the Pass Key system, which is pretty unique to Fbodys and vettes. The BCM reads the resistance from the chip in the key and if that resistance matches the one preprogrammed into the BCM's non volatile memory, the BCM will enable the crank relay allowing the starter to crank. At the same time it will send a "fuel enable" code to the ECM to enable fuel injector functions via class 2 data. Engine starts, everyone is happy.

If the BCM were to recieve the wrong code or no code at all with the ignition swtich in the crank position, the BCM will enter tamper mode. The BCM will not enable the crank relay and will not send the "fuel enable" code to the ECM. Every time the ECM sees a crank request signal, it looks to the BCM for the fuel enable code. If the ECM does not recieve the code, it will not enable the fuel injectors. Tamper mode lasts for 3 mins.

The whole purpose to linking the BCM to the ECM for VATS is so that you can't just throw any ECM (or BCM) into a car and drive away in it even though the chip in the key is the same. Its like a 2 layer theft deterrent system.

Other GM vehicle's theft deterrant systems operate slightly differently.

Jay

[joecar]

Zapp, Jay, ok, thanks... :cheers: