1996 UART?

[3100 MPFI]

does anyone know the BAUD RATE (I think that is the proper term) for the 1996 OBD2 PCM that was used in a 1996 Grand Prix?

This is for the UART, not the class 2.

Thanks

[3100 MPFI]

I have been reading, and I might not be asking the right question.

I need to know the format that the UART signal for the data line from the PCM to the ALDL works in the 1996 Grand Prix 3100 SFI PCM.

I am trying to hook up something to it, and it says that the older ECM will an 8192 BAUD will work, but that the 1996 is not compatible. I want to know WHY.

[Shadyman]

OBD2 is not the same thing as ALDL. ALDL was mid-1995 and earlier. OBD2 is its own set of protocols. Most GM and most Chrysler use the SAE J1850 VPW protocol. You can buy the protocol document from SAE, or you can get a kit from http://www.obddiag.net/multiadapter.html to connect via USB to your computer.

[3100 MPFI]

That is not quite what I mean.

1989-1993 has a certain data stream that certain things can read. It is called CLASS 1 DATA.

1994-1995 only has a CLASS 2 data.

1996 has both CLASS 1 AND CLASS 2.

What I am trying to hook up is a digital gauges cluster in my 1988 Cutlass Supreme that has a 1996 OBD2 PCM.

If I connect the digital gauges cluster data wire to the OBD2 CLASS 1 data stream, will the tach work?

[IsaacHayes]

Hmmm. Not sure if that will work... Cause I know people with the digital dashes the ECM code is made differently. I remember someone had a thread about their digital gauges not working in their beretta after a chip from Ben, and Ben said he would need to use the older ECM code for that to work as the newer didn't put out the right stuff in the ALDL stream.

Even if you can get that info, it would be different address,etc in OBD2 surely if just different OBD1 code can make or break the digital dash from working.

Might not be possible.

[3100 MPFI]

That is why I am trying to get the baud rate. If the 1996 class 1 (which is not used in the 1994 and 1995 obd 1.5) has the same rate, then in theory it will work.

I know that the digital clusters don't work in the 1994 and 1995, but since they don't have the class 1 for that year, then it seems that if the baud rate is the same for the 1996 class 1 (which is listed as UART, same as the 1989-1993), then it will work as long as the data wire is hooked up to the class 1 wire.

I still get the feeling that this is one of those things that I will never find out unless I do it myself.

[IsaacHayes]

You're missing another part of it. Even if the baud is the same, there is different hexidecimal addresses that the data is located in the stream. I'm not talking about 94-95 cars at all. That thread I was referring to was still the old eeprom cars. Just different computer code masks of the same car but different year will have different sensor values reporting. You can see this with a definition file in tunerpro, load the wrong one even if it's still the same engine and you might have RPM's reporting what the MAP sensor is /etc.

So you'd have to get incredibly lucky that the addresses that the gauges need to see are the same for 96 as in 88. Highly unlikely since they changed between years let alone different engines...

Too bad the digital gauges didn't run off analog inputs like the analog ones did. LOL. They had to be "fancy" and decode the ALDL stream hehe. I guess that was easier to have the ECM interpret the signals and just pull the data from it though than make another module to convert the signals.


So what's stopping you from hooking up the thing? I don't think it would fry anything if the baud rate was off. Might just get some weird readings or nothing at all. As long as the voltage/etc is the same and wires connected right.

[3100 MPFI]

nothing stopping me. In fact, it IS hooked up, but I can't test it yet. I have to do a few more things to the wiring and engine before it will be ready to attempt to start it.

I am just trying to get some information on this before I turn the key.

I have a feeling that there is other things that I will need to find out, but I feel like such a fish out of water. To the best of my knowledge, NO ONE has done an OBD2 conversion to a 1988-1993 w-body.

Worst case senario I will have to put the analog gauges cluster back in. No big deal on that one. I was just trying to figure this out now so that maybe I can also get my DIC working as well. I know the DIC does not work in the CLASS 2 cars, but I am hoping that the 1996 class1 will allow for some of it to work. I know the fuel will work, but the tach and engine data probably will not. I am just trying to find a way to get it so it will work.

[IsaacHayes]

Having a working DIC is important. LOL sorry I'm in a nutty mood. It will probably fail if the gauges fail. I doubt it will all work but maybe you are lucky?

[3100 MPFI]

not lucky yet, but I hope to get lucky REAL SOON.

I think I am in just as nutty of a mood as you are.