I am working on a project.

I need the UART data thats spit out of a 96 corvette PCM that is sent to the CCM.

I need this same data sent out of an '03 0411 PCM on the TAC UART data line.

Or I need to have this data sent out on the Class II and converted to UART.

I also need to take the ASR spark retard UART and feed it to the 0411 PCM.

AJ? Darth? Bueler?

UART...
Most use 16550 chip specs/format. They are used in PC serial(COMx port.
But many chips and USB units/cables doesn't like nonstandard GM ECM/PCM streaming...

To convert ECM TTL to RS232...
many use MAX232
Example www.techedge.com.au/vehicle/aldl8192/8192hw.htm

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

Yes sir!

I work with a lot of the PC serial type.

Have built a few of those MAX232 for the old school tuning days.

Both these computers where design to comply with one fo the OBD-II protocol standards.
here is one:
http://standards.sae.org/j1850_199507/

You betcha. They both follow OBD2 standard. As it was the requirement from 96 on.

More specifically guys, has anyone tried to load a different set of UART data onto a Class II PCM to make it backwards compatible with an older system?


This may be a bit technical for the average swaper/mech. Details can be seen here...Corvette Forum, 24x Conversion. By Merlot566jka

[This message has been edited by merlot566jka (edited 01-10-2013).]

quote Originally posted by merlot566jka: You betcha. They both follow OBD2 standard. As it was the requirement from 96 on. More specifically guys, has anyone tried to load a different set of UART data onto a Class II PCM to make it backwards compatible with an older system?

What do you mean? To convert OBD-II data to an older ALDL format (there were several) used by GM?

quote Originally posted by dobey: What do you mean? To convert OBD-II data to an older ALDL format (there were several) used by GM?

Yup, Class 2 (J1850 VPW, there were many 'OBD-II' protocols) into older GM ALDL 8192 protocol.

I think I found the answer, PIM module, by GM for the 04 GTO (holden).

quote Originally posted by merlot566jka: Yup, Class 2 (J1850 VPW, there were many 'OBD-II' protocols) into older GM ALDL 8192 protocol. I think I found the answer, PIM module, by GM for the 04 GTO (holden).

The Fiero itself doesn't even use the 8192 protocol. It's older and uses the even much slower than that protocol. But even the 8192 is still an order of magnitude slower than the current OBD-II systems. Why would you want to convert it to such a slow protocol? It's like using a 56Kbps modem to connect to the Internet via FiOS.

Also, the Class-2 serial bus, and the OBD-II protocols are separate things. Class 2 serial is a GM-specific protocol they used on top of their OBD-II vehicles to provide additional information and features. It is used on all modern GM vehicles, regardless of the main OBD-II protocol in use.

quote Originally posted by merlot566jka: Yup, Class 2 (J1850 VPW, there were many 'OBD-II' protocols) into older GM ALDL 8192 protocol.

Could you clarify this statement?

quote Originally posted by dobey: The Fiero itself doesn't even use the 8192 protocol. It's older and uses the even much slower than that protocol. But even the 8192 is still an order of magnitude slower than the current OBD-II systems. Why would you want to convert it to such a slow protocol? It's like using a 56Kbps modem to connect to the Internet via FiOS. Also, the Class-2 serial bus, and the OBD-II protocols are separate things. Class 2 serial is a GM-specific protocol they used on top of their OBD-II vehicles to provide additional information and features. It is used on all modern GM vehicles, regardless of the main OBD-II protocol in use.

I am working on a 1996 corvette and swapping in a 0411 (2003 LSx) PCM. The 92-96 corvette uses 8192 protocol to communicate with its PCM, ABS/ASR and CCM (similar to a BCM).

Yes, OBD2 is an industry defined set of requirements. Class 2 is just GMs version of serial data communication. It just so happens that GM started using their Class 2 when OBD2 came around. They (GM) have since changed their bus system several times, while OBD2 requirements have remained the same across the industry.


Phonedawgz
To clarify, The many protocols used by several manufactures differ greatly. GM uses j1850 VPW. This information is too great to write in this post, and can be had from the SAE documents on the OBD2 requirements white pages.
My objective is to translate GM J1850 VPW protocol into older GM ALDL 8192 protocol to use a newer pcm on an older system.


Forgive me for posting something not 100% related to the Fiero. I just know where there are some experts and I came to the place to find them.

To relate this to a fiero, the corvette is parked next to the fiero in the garage....

quote Originally posted by merlot566jka: I am working on a 1996 corvette and swapping in a 0411 (2003 LSx) PCM. The 92-96 corvette uses 8192 protocol to communicate with its PCM, ABS/ASR and CCM (similar to a BCM). Yes, OBD2 is an industry defined set of requirements. Class 2 is just GMs version of serial data communication. It just so happens that GM started using their Class 2 when OBD2 came around. They (GM) have since changed their bus system several times, while OBD2 requirements have remained the same across the industry. Phonedawgz To clarify, The many protocols used by several manufactures differ greatly. GM uses j1850 VPW. This information is too great to write in this post, and can be had from the SAE documents on the OBD2 requirements white pages. My objective is to translate GM J1850 VPW protocol into older GM ALDL 8192 protocol to use a newer pcm on an older system. Forgive me for posting something not 100% related to the Fiero. I just know where there are some experts and I came to the place to find them. To relate this to a fiero, the corvette is parked next to the fiero in the garage....

I think you're very confused about how the systems actually work. You're trying to use a 2003 ECM from an LSx equipped car to control an LT1 or LT4 engine in a 96 Corvette? Please explain exactly what you're trying to do, rather than making vague assertions about how the systems work.

He is trying to not only control the engine, but keep the BCM, PCM(TCM), and entire electrical system happy with the LAN framework.
The first step I would take would be trying to get in a GM tech LAN and CAN class, since I know nothing about thier systems.

So does the 8192 protocol operate on the same one wire electrical standard that the ALDL connector operates on? If so communicating with it electronically should be simple.

What kind of a processor are you looking to use for this communication translation?

The arduino mega has multiple serial inputs and outputs. You would have to code in the translations but it sounds feasible.

quote Originally posted by FieroWannaBe: He is trying to not only control the engine, but keep the BCM, PCM(TCM), and entire electrical system happy with the LAN framework. The first step I would take would be trying to get in a GM tech LAN and CAN class, since I know nothing about thier systems.

GM-LAN and CAN are only used on GM vehicles from 2004 on (and not all vehicles until 2008, when it became mandatory for all US automakers to use CAN).

I'm pretty sure the 96 Vette uses the older Class 2 bus for sensor communications.

quote Originally posted by dobey: I think he's confused. The ALDL 8192 communications was OBD-I only. I'm pretty sure the 96 Corvette (and the 2003 as well), used the Class 2 bus for all the internal communications.

No confusion here sir. While yes, the older computers used 8192 for all communications, the 1996 corvette was different. As you may recall, the in the 94-96 time frame multiple GM vehicles were identified as having an obd 1.5 system. They had an obd 2 connector, but were still obd1 data and mostly 8192. Later, in 1996 these vehicles became bastards, as they had no parent protocol. Some used both UART and J1850. Yes, they had BOTH. The 96 corvette had Class 2 to access obd2 commands/data, but the entire cars bus network was a separate 800 series UART, just like the 90-95 corvette. Which makes tuning a total nightmare. Which is why I am swapping to the 2003 pcm.

And to add, the 2003 corvette PCM also has 8192 UART for the TAC (throttle actuator control) bus system. The 04 GTO has class 2, and 3 UART busses. The 05-06 GTO has Class 2, CAN, and 3 UART data busses...

The confusion is only on the side of the uninformed...
From WIKI OBD basics
OBD-1.5
OBD 1.5 refers to a partial implementation of OBD-II which General Motors used on some vehicles in 1994, 1995, & 1996. (GM did not use the term OBD 1.5 in the documentation for these vehicles — they simply have an OBD and an OBD-II section in the service manual.)
For example, the 94–95 Corvettes have one post-catalyst oxygen sensor (although they have two catalytic converters), and have a subset of the OBD-II codes implemented. For a 1994 Corvette the implemented OBD-II codes are P0116-P0118, P0131-P0135, P0151-P0155, P0158, P0160-P0161, P0171-P0175, P0420, P1114-P1115, P1133, P1153 and P1158.[5]
This hybrid system was present on the GM H-body cars in 94-95, W-body cars (Buick Regal, Chevrolet Lumina ('95 only), Chevrolet Monte Carlo ('95 only), Pontiac Grand Prix, Oldsmobile Cutlass Supreme) in 94-95, L-body (Chevrolet Beretta/Corsica) in 94-95, Y-body (Chevrolet Corvette) in 94-95, on the F-body (Chevrolet Camaro and Pontiac Firebird) in 95 and on the J-Body (Chevrolet Cavalier and Pontiac Sunfire) and N-Body (Buick Skylark, Oldsmobile Achieva, Pontiac Grand Am) in 95 and 96 and also on '94-'95 Saab vehicles with the normally aspirated 2.3.

For ALDL connections, pin 9 is the data stream, pins 4 and 5 are ground, and pin 16 is battery voltage.
An OBD 1.5 compatible scan tool is required to read codes generated by OBD 1.5.
Additional vehicle-specific diagnostic and control circuits are also available on this connector. For instance, on the Corvette there are interfaces for the Class 2 serial data stream from the PCM, the CCM diagnostic terminal, the radio data stream, the airbag system, the selective ride control system, the low tire pressure warning system, and the passive keyless entry system.[6]

The F-bodies were alike, but didnt use the data bus as much as the corvette did...