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View Full Version : How do I perform VATs to BCM Relink?



KAZ MotorSports
May 8th, 2008, 11:55 AM
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
May 8th, 2008, 01:13 PM
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
May 8th, 2008, 01:39 PM
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
May 8th, 2008, 06:48 PM
Be sure to talk to EuroSpec and Doc: showthread.php?t=7992 (http://forum.efilive.com/showthread.php?t=7992)

KAZ MotorSports
May 8th, 2008, 11:31 PM
Will do. This is a great learning experience for me and I am actually enjoying it.

Thanks for your advice Joe,
-Kenny

1998ws6
May 9th, 2008, 05:57 AM
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
May 9th, 2008, 06:03 AM
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
May 9th, 2008, 12:53 PM
Glad your up and running, :) It makes it much nicer to tune, especially with a roadrunner.

Ryan

joecar
May 9th, 2008, 12:55 PM
+1

And he can run COS5 if he wants to. :cheers:

joecar
May 9th, 2008, 12:58 PM
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?

RyanYou 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

1998ws6
May 10th, 2008, 01:09 PM
F-cars 98-02 use the 5volt 50hz square wave.

Y-cars (corvette) , and trucks use the serial data bus.

Ryan

joecar
May 11th, 2008, 08:02 AM
Ryan,

You're right again... I was looking only at the Vette wire diagrams, I should have looked at the F-body ones too.

When I replaced my 411 PCM with my spare 411 (from another vehicle), I got no start until I did a VATS relink... wouldn't the same thing happen with a 98->411 conversion...?

Cheers,
Joe [learn mode=on]
:cheers:

1998ws6
May 11th, 2008, 11:41 PM
If flashed for a f-car OS, verify the theft settings are on PWM and it should start fine. If setup for a Y/Truck, it will fail, due to looking for the BCM on the serial bus.

If you get an issue with that, you can just turn off the antitheft, but it should be be necessary.

One thing to verify, is make sure your 98 pcm didn't have the theft turned off, as many times people even with stock cars will turn off the theft system, when they have a problem with the key as they get older, as it is much cheaper than fixing the tumbler correctly. I do not know your history on this vehicle.

Looking at the convert98.doc by Chips by Al, step 22,
"22. Red C1-11 DK BLU TO Red C2-30"

looks to be the fuel enable singnal, verify this wire is in the correct location to get the 5volt 50hz enable signal to the new ecm.

Hope this helps.

Ryan