3. Regarding communication with the CCM, I initially thought that this was going to require fabrication of an interface. The Gen III PCMs communicate via the Class II protocol and the ECM, CCM and other modules in our cars communicate via 8192 baud UART. The CCM acts as the master device in this arrangement and is the only device that the ECM communicates with directly. After lots of research, I recently found out that GM (Pontiac GTO) and Holden have produced cars with Gen III PCMs coupled with vehicle systems that utilized 8192 baud. They have a plug and play module called a Powertrain Interface Module (PIM) which translates between the PCM Class II and CCM (or BCM in later vehicles) 8192 baud protocols. While some code mods may be required so that the PCM can understand the CCM messages and respond aprropriately (speak the same dialect), the PIM will allow them to communicate at the hardware level (speak the same language).

From http://zr1.net/forum/archive/index.php/t-16757.html

 

More about the PIM
http://www.thirdgen.org/techboard/po...211-post6.html

 

http://www.ls1gto.com/forums/attachm...1&d=1307401338

http://www.ls1gto.com/forums/attachm...1&d=1307401315

These are the PIM ins and outs. Looks like the ccm issue is resolved...

 

I am a pretty savvy dude an you have given me plenty to study.
I am committed to make this work somehow. Thank you for the input.

 

This is the mother of all explanations on GMs data streams and history of each. This is a good read.

http://tomboynton.com/GMnetworks.pdf


In case you are like me...
UART toutorial
http://www.freebsd.org/doc/en_US.ISO...art/index.html

This explains how the communication between ccm, PCM, code readers and the like work.
I can easily see how we can make things work now. The PIM can probably be homemade.

 

 

Awesome work, this is great news

 

I like the 24x conversion. Wish it was around back when i did my gen 7 setup but i must admit I probably would have went gen 7 / FAST anyways if I had to do it again.

With my first engine i ran a dual sync duistributor in the back of the LT4 manifold. With this second build I am running an msd pickup welded into the gm timing chain on the cam gear with a magnet for 1x and and should get my new ATI damper shell with embedded magnets for 4x soon from ATI to run full sequential without any magnets and sensors right under a small cap dizzy.

A few pics of my setup.. 10 year old pics forgive the quality at about 30s in the video
http://www.youtube.com/watch?v=nwnL5ouKLno

having said that i love the idea of an LS pcm. There are tuners everywhere that are familiar with it and imo that is the BIGGEST advantage that it has. On the other hand having noone to tune my car and having spent countless hours at night doing (fun) datalogs (4th gear pulls to 8k rpm 3.73 gears ..) I wouldnt have had it any other way than have learned to tune my car myself.

 

No updates from the weekend. Spent time with the kiddo.

This week I am going to expore the idea of using the optispark timing wheel. Cutting the pattern of the lsx 24x wheel (x2) into the the high resolution side of the opti, should provide the same signal as when the lsx crank signal used. I have found (from the stuff posted in this thread) that the double wheel was only for checking and noise elimination, which we wont have on an optical sensor. may have to move things around to get the high-low or low-high... no one is really certain which the sensor actually needs.

For the 1x cam signal, I want to use the low resolution side of the opti, cutting about 1/2 the wheel for the pattern. this will mimik the cam signal. I dont have exact signal for the cam yet, ive seen some variations and im not certain what the ls1 used. i think the other ls engines had a variety of cam signals.

The advantage i see here is plug and play ability with slight work on the engine, but no different than you would have to do to change the opti. This also eliminates the need for more sensors/connectors. this also allows for conversion back to stock and a huge reduced cost.


As for the PCM to PIM to CCM, I dont have those parts on hand, nor have discovered anything new. I am going to shoot a few emails out this week to see what I can get accomplished as far as research. I will contact HPTuners, Sinister Performance, and maybe some other reputable tuners. I am looking to see if the lsx PCM will put out the data that the PIM needs to send to the CCM, and whether the PIM needs to be modified to send the info that our CCM uses.
There may be some hang ups here for year to year differences on cars... as I am pretty sure the 96 CCM was different from the 92-94.

Anyway, back to work.... Let me know if you guys have any info or questions....

-Jonathan

 

I have been reading up on this A Lot..there are a few things that bother me.
1. The different baud rates. OBDI vs OBDII
2. The UART vs CAN is it really possible to translate the data especially considering the modules have codes they are expecting to hear in order to communicate.
3. The OBDI data stream has a start and stop kinda like Morris code if you will. CAN is more like moderns networks with everything talking over the bus.

I'm going by memory right now I don't have my notes in front of me.

However looking at the CCM and the data that is feed to it. I started wondering what it really does with it. It takes in VSS and Serial data at 4Kppm and that is the same as the LS1 PCM is providing. So soon we will know what is going to work and what is not. My wiring should be done in a week or so.

 

1. Stop and think, can a fast computer talk to a slow computer? SURE. They are at the same clock speed, its the information that the fast computer provides can just be moved faster (more at the same amount of time) Look at it this way, can a laptop talk to an obd1 ecm? how? its so much faster. the usb port has a baud rate of 192 kB/s... and an obd1 at 8190... how on earth can they talk...? This is where you need to understand how serial data works. Its not water running through a pipe, its much more complex.

2. The difference between UART and Class 2 communication was explained in this article, http://tomboynton.com/GMnetworks.pdf. Further understanding of UART language, and Class two can be found online.
BUT, the answer is YES. The PIM module in the ls2 GTO does exactly this. It takes the Class 2 data (not CAN, that was later as I have found out from the article hyperlinked above) and uses this data to talk to other modules that are on the UART setup. This is easy to say it works, but to explain what it does with the data sent, responses, pauses between, offline status, etc etc. is another story, and would require me to have a PIM, the ls1 PCM and ltx PCM in hand and everything all mapped out.
Just knowing that the perphiels in the GTO opperate on UART and use the PIM translates Class 2 data into and from UART, I know that "there is a way" and "this is how GM does it"

3. OBD1 and OBD2 have nothing to do with the serial data. OBD1/2 have to do with the standardization of troubleshooting on cars computers, and the point in time in which it happened. Any change in serial data from OBD1 to OBD2, in any vehicle, is a coincidence. As demonstrated by the fact that the 96 PCM still uses UART to communicate with the CCM and it is OBD2.
That said, the UART communication is well explained in the article I posted above, and even more so here http://www.freebsd.org/doc/en_US.ISO...art/index.html . Reading this, and understanding some basics about computers, we can easily assume that there is the ability to have a computer take a sort of information and do something with that information. Well is it not to hard to assume that we have a device, a computer, that will take a bit of information that is in Class 2 protocol format, and send it out modified into UART language? Could this device also work the other way around and take UART and change it back into Class 2 data?
Is it possible to have something that could interface serial data? ... absolutely.

But before I go any further, What is pin 3 on the blue connector of the LS1 pcm? Thats right, 800 series UART data.
What is on Pin 58 of the blue connector, Class 2 series data...

Heading home from work, will investigate more later.

 

wiring data for lsx to lt1 from efi connections, this is for a 99 ls1 pcm
http://ls1tech.com/forums/lt1-lt4-mo...lsx-pcm-2.html

also, http://ls1tech.com/forums/conversion...cm-pinout.html
says that pin 14 on this later (99 ls1 pcm) is the UART serial data.

So im seeing variance in lsx pcms, no matter, just have to sort out the details. What I do see is that the lsx pcms do infact have a serial data comm for UART....

 

pin 3 on the Blue connector is INJ 2.

 

On PCM # 16238212
1997-1998 ls1 PCM
Pin 3 is serial UART data.

I should have clarified which year.

From ChevyThunder.com

Kind of blurry, but this is a screen shot of the ChevyThunder site

 

this is some more info



from the horses mouth.

less pert info, but still more on the PIM





what I am taking away from this is that the LS1 pcm from the GTO (Holden cars) provides serial UART data. This data can be manipulated to emulate the ltx UART data...I THINK. Also the PIM takes the data from the Class II and changes it into info the (newer) BCM uses. How and what this PIM does, is still uncertain, but as it says here, it converts the data... which data and can we use the converted data, I dont know yet.

This data and more is available here: http://www.sr510.com/tech/Holden_LS1.pdf
on page 21-23. this is a large pdf

 

Mine does not appear to have this.. I need to do more digging.

 

Your 'what' doesnt have 'what'?

 

Did you loose track.
My 99 PCM does not have a UART data output as far as i can tell. I'm going to keep digging. I could always swap out for a 98 PMC but that would require repining over 100 wires and a flash. Thanks for the help.

 

check pin 14

 

It's worth a shot
Ill let you know how it works out.