How do I perform VATs to BCM Relink?

[KAZ MotorSports]

Hey guys,

I just got the 411 PCM into the 1998 T/A. I reflashed the VIN#, uploaded a 2002 T/A cal with COS-3, and made sure the PCM was taking the information on a bench harness. Everything worked great there.

I plugged the PCM into the "new/repinned" harness and I can not connect from the OBD2 port/laptop to the PCM. It does not see it, but if I connect/disconnect the (-) terminal on the car's battery I get the "dong" sound from my laptop like I unplugged the cable from the OBD2 port or laptop.

I am assuming the only thing left is to do a VATs to BCM relink? How is this procedure done with the Scan-Tool?

If I am way off base and need to look at other comm issues as to why I cannot link to the PCM through the OBD2 port...please chime in. I did verify that all of the pins are going where they are supposed to...but will be checking again in the morning just in case.

Thanks guys,
-Kenny

[joecar]

Kenny,

Since you had comms on the bench harness, the comms problem has to do with the car harness/connectors/power/grounds.

VATS will not inhibit comms, but VATS will inhibit fuel injectors and possibly starter.

You need comms to do the following:

First use the scantool to write the VIN to the PCM: Bidirectional->Change VIN.
Then use the tunetool to do the VATS-BCM relink: Flash->PCM Security->VATS Relink.

After doing those 2 steps, car should start and run.

When warmed up, you may want to do CASE relearn (from scantool) to allow misfire algorithm to work correctly.

[KAZ MotorSports]

Well considering the repin/rewire looks like a mess I will redo it all tomorrow "cleanly" and see what happens. The more I thought about it I would not be surprised that I have a wire or two with a little too much tension on it.

Quite a pain in the balls doing this on an F-body. I saw Doc and Rick's pictures of the C5 they did with everything looking so organized and tried to follow their lead. Seems that a C5 or a Vortec truck will be cake compared to this.

Alright...off to bed so I can get up before the sun.

Peace,
-Kenny

[joecar]

Be sure to talk to EuroSpec and Doc: showthread.php?t=7992

[KAZ MotorSports]

Will do. This is a great learning experience for me and I am actually enjoying it.

Thanks for your advice Joe,
-Kenny

[1998ws6]

You do not need to do a relearn for that conbination, the BCM uses a 5 volt 50hz square wave to send the fuel enable signal to the pcm.

I did the same swap on my car, without any issues. What wires do you have not connected to the 98 pcm?

Ryan

[KAZ MotorSports]

In Al's .doc at the bottom it states that Red C1-60 BRN, Blue C2-19 PNK (PCM IGN Feed), C2-58 PPL (Serial Data), and C2-20 ORN (PCM BAT Feed) remain in the same locations. I labeled them as stated above and plugged everything in...not paying attention to the COLOR code swap, just putting them to those pin locations!!

If the PCM is not powered, told to switch on, or have a serial data link it makes no wonder why I could not communicate with it.

[1998ws6]

Glad your up and running, It makes it much nicer to tune, especially with a roadrunner.

Ryan

[joecar]

+1

And he can run COS5 if he wants to.

[joecar]

You do not need to do a relearn for that conbination, the BCM uses a 5 volt 50hz square wave to send the fuel enable signal to the pcm.

I did the same swap on my car, without any issues. What wires do you have not connected to the 98 pcm?

Ryan

You are correct, I see that the 1998 BCM has a dedicated wire for the 5V 50Hz "signature" whereas the later ones sent the signature via Class 2.

So he should simply disable VATS in the PCM then...?


Cheers
Joe