Originally Posted by jimter
I found a interface and software that should do what we need, now who wants to spend $1600.00
http://www.dgtech.com/products/jnat.phtml
Can you edit and reprogram an OBDII GM PCM with this?????? can someone please verify?????
Thanks
DANG! Lost my (rather extensive) email AGAIN.... Hey magnus... why not have the page not loose what you've typed when you have to backtrack to fill out you name, etc, when asked to after submitting a response?
O.k. So, as I WAS saying (again), tell me if I'm correct, My idea, is to have a controller that will buffer up to 64K bytes (64K would be as easy as 4096) and then send them out continuously... and be capable of going in both directions, rs-232 to j1850, and j1850 to rs-232.
Does this sound like something that would be of interest?
works for me!
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O.k. Sorry for the extremely stupid question, but, before I go off and build/design it, what will this thing allow people to do? I'm guessing to reprogram the firmware inside the pcm (with some aftermarket firmware???)
ALso, will the 4096 bytes be continuos? (not framed in 12 bytes?)
I'm also guessing, it will allow you to sniff and log it... for later diagnosis?
Will it HAVE to be 40.6 baud compatible or will 10.4 be acceptable?
I realize that it has been several months since you posted this, but I have both OBDII carputing and Autotap V1 hardware. I can check tonight when I get home, and let you know what chip they use.
sounds good to me! I've been ignoring the OBDII stuff and playing with my 93 lately - I almost forgot about that!
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The carputing hardware for OBDII that I have uses a motorola XC68HC58FN, a MAXIM MAX232ECPE, and another chip that's been sanded(to cover their tracks?). I could probably draw up a schematic of the board if I wanted. It's a simple two sided board, that anyone could make in their basement.
the max232 chip is a serial communications chip..
The motorola chip appears to be a CPU or a PIC? (gotta look it up I guess)
The other is probably the important one - that would most likely be the VPW communications chip.
Dont bother with a schematic - it would be easier to build around a new design. But now I know thats not just a 'dumb' cable - its got some command and control over the communications
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Ok, so I've spent some time reading throught the SAE J1850 spec, and it only talks about VPW(10.4kbps), and PWM(41.6kbs). So I'm assuming the "4x" mode everyone is talking about is actually the PWM. Is this correct? Another question I have is, where did the idea of Block transfer come from? Is it something someone notice while sniffing a Tech2? Any info about or link to an explanation of block transfer would be appreciated.
thanks,
Josh
Has anyone thought about how Hypertech communicates with the OBDII? I mean their programmer doesn't do a whole lot, but it still does program the car.
Whatever they do, it looks like it may be cheaper to implement something similar to their design.
For what it's worth though, they use the same processor Carputing uses - XC68HC58FN and there's a couple bigger ones. One of the bigger ones is a Motorola too and the other I think has their non-eraseable firmware. Then there's their flash chip which isn't interesting, but nothing else other than that really. So how do they communicate then?
OK, the other chip on the Hypertech board is a MC68HC11EDOCFN2. There's also two 14 pin SOP chips that can be found on the PCM boards and an 8 pin chip that has this written on it:
"ADM707
AR
9810"
The only other chips is one that isn't relevant, the flash chip and the chip that stores their current revision. (WSI PSD312-B-12... did a search on it and couldn't come up with anything)
the ADM707 is a supply voltage monitor, and the WSI PSD312-B-12 is a Low Cost Field Programmable Microcontroller Peripheral, made by WaferScale, which is now owned by STmicroelectronics. Do a search for PSD312 on ST.com for data sheets.
OK so after reading this thread I came up with an idea. Wouldn't it be easier to create a software or hardware version of a sniffer that looks for the command that requests the VIN then just pump in the same VIM over and over again basically unlocking lsedit and other programs that only allow you to use the program on one VIN number?
Those "programs" don't look for the VIN number only.
the 68hc11 and 68hc58 are different microprocessors but they probably do the same thing
That PSD312 is very interesting.... reading up on it now... or at least on PSD devices. The 312 seems to pull up the 813 for some reason.. >
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That's explicitly illegal. I don't think that's what this board is about.
Sorry didn't mean to suggest anything like that. Just trying to get some info here. I would love to be able to do the simple things that ls1edit and other programs allow you to do like edit when the fan turns on defeat the CAGS.
You can buy chips from Motorola that speak J1850 for GM and handle all the buss stuff. You just give it the commands. Go to Motorola's semiconductor site and do a search for J1850.
Of course, you can use the SAE spec and emulate it yourself, but that's alot of work.
The motorola chips take care of the hardware side, but you still need to understand the SAE J1850 spec to communicate with the PCM.
[quote author=me]The motorola chips take care of the hardware side, but you still need to understand the SAE J1850 spec to communicate with the PCM.[/quote]
Yes, but communication is easy. Fingering out the GM seed encryption that unlocks the areas we need to write to is the hard part.
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