Pcm replacement with aftermarket scanner?

[DodgeTransmissionsGoBoom]

I jacked up one of the electrical connectors on the pcm the grey plug after cleaning them with qd cleaner. The cleaner caused the gasket to swell too large to fit and when I went to install the plug after drying it slid in half way and made a very disturbing pop instead of the satisfying click. Pulled it back out and found all four round nubs had broken off on the pcm fml... I boiled the gasket to shrink it back down and put a super thin coat of grease on it and it slid in all the way and is holding strong but doesn't have anything locking it down. I can get a junkyard pcm near me for about 45 bucks but I'm not sure if my scanner will rewrite the vin number. I've programmed keys for a salvage ford with no other known keys in the past with success. But I'm not sure if gm requires the entire software to be reflashed for a vin to be changed. It's a 2008 tb 4.2l. the scanner I have is an x431v+ costs about $1200. Not sure if it's expensive enough to do the job it has basically done everything else I've thrown at it though I just don't want to risk buying a pcm and finding out I can't do it. I feel sure someone has tried this before.

Here's the scanner I have

https://www.amazon.com/dp/B00NID586M/?tag=gmtnation-20

 

[DodgeTransmissionsGoBoom]

I jacked up one of the electrical connectors on the pcm the grey plug after cleaning them with qd cleaner. The cleaner caused the gasket to swell too large to fit and when I went to install the plug after drying it slid in half way and made a very disturbing pop instead of the satisfying click. Pulled it back out and found all four round nubs had broken off on the pcm fml... I boiled the gasket to shrink it back down and put a super thin coat of grease on it and it slid in all the way and is holding strong but doesn't have anything locking it down. I can get a junkyard pcm near me for about 45 bucks but I'm not sure if my scanner will rewrite the vin number. I've programmed keys for a salvage ford with no other known keys in the past with success. But I'm not sure if gm requires the entire software to be reflashed for a vin to be changed. It's a 2008 tb 4.2l. the scanner I have is an x431v+ costs about $1200. Not sure if it's expensive enough to do the job it has basically done everything else I've thrown at it though I just don't want to risk buying a pcm and finding out I can't do it. I feel sure someone has tried this before.

Here's the scanner I have

https://www.amazon.com/dp/B00NID586M/?tag=gmtnation-20

Also what does the grey plug do exactly? I know the blue one is for the tcm. I just wonder if the grey plug happens to work its way loose somehow if it would cause the vehicle to stall or if it would just cause some fault codes and possibly limp mode?

 

[Mooseman]

You don't really need to rewite the VIN to the PCM. If the PCM you get is for the same year and gearing, you can just hook it up and do the 30 minute security relearn which you would need to do either way. It will however need a CASE relearn which your scanner is capable of.

 

[DodgeTransmissionsGoBoom]

You don't really need to rewite the VIN to the PCM. If the PCM you get is for the same year and gearing, you can just hook it up and do the 30 minute security relearn which you would need to do either way. It will however need a CASE relearn which your scanner is capable of.

What's a case relearn is it for the immobilizer? Or for a different thing? Also will it mess with the emissions test? The state computer pulls the vin from the obd2 port to see if it matches what's on the scanned registration. If it doesn't it's an automatic fail. Unless the vin is stored in a different module

 

[DodgeTransmissionsGoBoom]

What's a case relearn is it for the immobilizer? Or for a different thing? Also will it mess with the emissions test? The state computer pulls the vin from the obd2 port to see if it matches what's on the scanned registration. If it doesn't it's an automatic fail. Unless the vin is stored in a different module

Just got a reply from the manufacturer. They say the tool can do it. Hopefully it does if I need to do it.

 

[Mooseman]

What's a case relearn is it for the immobilizer?

Crankshaft Angle Sensor Error, aka: crank angle variance relearn.

Also will it mess with the emissions test?

Yes. Will set a code for it if not done.

he state computer pulls the vin from the obd2 port to see if it matches what's on the scanned registration. If it doesn't it's an automatic fail. Unless the vin is stored in a different module

When we had the e-tests here (been abolished a couple years now), I had swapped the PCM in my 02 TB. When they saw the mismatched VIN, they just had the tech show the vehicle's VIN via a webcam to prove it was the correct vehicle being tested. This would be for the case of PCM replacement. I guess your state testing is different and more stringent.

As far as flashing the new PCM, your tool may be capable however you may need an ACDelco TDS subscription for the vehicle unless it already has a library of stock tunes.

Site Maintenance

 

[DodgeTransmissionsGoBoom]

Crankshaft Angle Sensor Error, aka: crank angle variance relearn.



Yes. Will set a code for it if not done.



When we had the e-tests here (been abolished a couple years now), I had swapped the PCM in my 02 TB. When they saw the mismatched VIN, they just had the tech show the vehicle's VIN via a webcam to prove it was the correct vehicle being tested. This would be for the case of PCM replacement. I guess your state testing is different and more stringent.

As far as flashing the new PCM, your tool may be capable however you may need an ACDelco TDS subscription for the vehicle unless it already has a library of stock tunes.

Site Maintenance

I'm pretty sure it can't reflash it doesn't have that j box pass thru on it. I've noticed on some vehicles it has a vin change button under the ecu section but I'm not sure if gm is the same way or if the entire software has to be reflashed.

 

[TollKeeper]

Isnt there a way to pull the coding or whatever off the old, and write it to the new?

Still rather new to the OBD2 stuff, so forgive the question.

 

[DodgeTransmissionsGoBoom]

Isnt there a way to pull the coding or whatever off the old, and write it to the new?

Still rather new to the OBD2 stuff, so forgive the question.

Usually you need some kind of custom bench programmer or a way to extract the code of the current pcm then save it to your computer then flash it to the new one. I don't have equipment capable of doing that sadly

 

[Mooseman]

Check to see if your tool can do passthrough programming if it support the J2534 standard.

J2534 Tools

There was a bit of a discussion started on another thread about J2534 tools. I have one and it works pretty well. You just need pretty decent laptop to run it. I have the Cardaq Plus 2 made by Drewtech. It is kind of pricy but I work on so many different makes of cars, it is worth it to me. They...

gmtnation.com

 

[DodgeTransmissionsGoBoom]

Check to see if your tool can do passthrough programming if it support the J2534 standard.

J2534 Tools

There was a bit of a discussion started on another thread about J2534 tools. I have one and it works pretty well. You just need pretty decent laptop to run it. I have the Cardaq Plus 2 made by Drewtech. It is kind of pricy but I work on so many different makes of cars, it is worth it to me. They...

gmtnation.com

Nah it doesn't have anything like that

 

[Billdaman1]

Nah it doesn't have anything like that

I have the Launch 431V and its a fantastic bidirectional scanner. Had it two years and will be getting my last updates on Jan 4th. After that no new updates, but I use it on pre 2020 vehicles so that wont be a problem.

I would like to try replacing my ECM with a junk yard version to see if it fixes drivability issues. I also have had a few codes thrown over the years related to internal ECM fault where the truck would just die and be a bitch to start for 30 seconds or so.

Have you tried to use the Launch 431V to do this reflash yet?

 

[JayArr]

Can you solder?

The cheap alternative is to remove the connector from the junkyard PCM and solder it into the original unit. Assuming everything is OK with the unit besides the broken connector.

If you can't solder maybe a local electronics shop will do it. I take in jobs like that from locals all the time, it's about an hour of bench work.

The even cheaper way would be to buy a bag of tie-wraps and zip tie it so the plug can't fall out.