I would like to know who else has the ability to reflash an OBDII GM PCM...

Thanks

 

Right now carputing has the only software I know of for obdii. I've heard Tunercat well have a obdii def file in March of this year.

 

Its not just a def file... They need a cable that has the ability to do block transfer and 4x speed...

The bb-elec cable works for 4x speed but no block transfer...

No cable.. no program...

I understand that carputing deciphered the cable the hard way...

 

The cable/hardware to communicate with the PCM is a standard SAE protocol. I would think the hardware to communicate would be the easiest thing to develop. The hard part would be mapping out the PCM.

 

actually no... It is not a simple protocol.. The diagnostic part is, since it is a standard... but to write to the PCM it is not a standard per se and the cable has to be developed... If you can find out about a cable that can do the block transfer and the 4x speed I will gladly appreciate it

 

Cable/Hardware is the easy part. the protocol and command and control of the pcm is a software issue.

 

Get me the hardware and I'll have the software ready... where can I get the hardware that can communicate correctly to do reading and writing to the flash of the pcm and we will be set with a software vin unlocked... lmk

 

Have you asked the DIY EFI guys yet?

 

Highlander I am not sure of the exact specs of the ALDL but I am certain it is just another Serial communications link similar to many Serial I/O devices available in the Electronics market now. Kind of like an ISO Smart card. Probably a Bi-directional Serial I/O line, clock, VCC, Ground. I am guessing at this but someone somewhere should have this data. I just looked through my Haynes and cant find anything on the ALDL connector.

 

No its not similar... it must go into 4x mode (41.6kbps) and It must do block transfers...

Its not a simple harness..

 

I recently asked TunerCat via email, and they said they are working on it and should have it out in a month or two! Yay!

 

Can you be a little more specific... ie what do you mean by 4x mode being 41.6kbps?? and by block transfers i assume you mean that the interface will transfer information in 1k or so blocks. Do you have a wiring diagram for the connector showing the lines description? or anything related to the ALDL for OBDII. I can recall thinking that OBDII is standardized across all manufacturers. So that would lead me to the assumption that there is information out on the net on communication parameters. I have been a hardware integrator for a number of years and can make any technology adaptations work. I found a couple of references to OBDII specifications manuals by the SAE. Look at this link and tell me what you think

Link 1 this is the 1999 version

Link 2 this is the 2003 version



I can see from some other specs i have found that the communications packets are very similar to an older technology i used several years ago called a Motorola S-Record Communcations protocol that was used by a CNC Machine Tool I was servicing, basically they consist of a variable length "packet"
that contains header, data, and a checksum. Within the header there is data that sets up the data length, types, etc.

Another reference I found is at this
Link to B&B OBDII specs

I have not spent a ton of time researching this stuff But I am curious as to what you are looking for, are you a software guru?. are you interested in developing a OBDII programming interface? Or just looking for an alternative to shelling out $550.00 for LT1_Edit for OBDII. I can make the hardware it is a "simple" thing for me. The software side is not for me though as I hate writing code. Talk to ya later, I am gonna turn in for the night.

 

Sweet! Haven't seen you here around much lately!?

 

Hey Will! I've been around reading, just not posting as much (haven't had much to contribute lately).

You guys can email tc@tunercat.com for more info on their OBDII tuner that I mentioned.

 

Well to update this thread, I have come up with a OBDII communications circuit design that is relatively inexpensive, and very impressive. It is designed to work with all three OBDII comm protocols, PWM (Ford), VPW (GM,Chrysler), and ISO-9141-2(european/asian). The hardware should not cost too much and is based on a PIC microprocessor. and a LM339 Quad comparator. a few transistors, voltage reg., caps, and resistors, it will communicate with a serial pc through a 3 wire connection (no handshaking). It will communicate with the PCM through the ALDL. If anyone is interested in more details drop me an email. I would like to see if we can develop a program of our own to tune an OBDII vehicle. Of course the F-body would be first on my list