Ahoy, so I have downloaded WinALDL.. but it appears to only work for 160bps ECMs. The 1227748 is 8192bps. I downloaded TunerPRO (and RT). I have an ADF file from Red Devil ($48), which does load. But TunerPRO wants an XDF file. Not even sure what that is.. and none seem to be provided by tunerPro or Red Devil. Searching forums seems to reveal a hole here. At PCMhack, there seem to be some files, but I would have to join to get.. not even sure if they are the right ones. I built the cable, read to go there.. Help?
1227748 ECM have high data speeds and use ALDL pin M to output data.
------------------ 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)
Agreed, I see the pins in the connector. I think that I am ready with the hardware.. ALDL to RS232 plus RS232 to USB.. ready to go. My real issue is figuring out what software to use, and if TunerPRO, how to get the files to make it work for 1227748.
I found the $48.xdf file at.. http://www.gearhead-efi.com...ighlight=1227748+xdf And at least the software is operating, expecting my ECU. Now the issue is figuring out if my home brew cable can work with TunerPRO RT.
xdf file is not needed for scanning. It is only used as a definition as to how the data is arranged on the PROM. The .bin file is the data that would actually be on the chip.
Only the .adx file is needed for scanning.
Early 80s ECMs (all Fieros except the 87-88 2.5) use a unidirectional data flow. The 10k resistor in the cable signals the ECM to send data. Data is then sent on the single communications wire of the ALDL connector. GM commonly used pin E for this configuration. The early ECMs only spit out the data about once per second. No data is sent from the scanning device to the ECM (other than the presence of the resistor).
Later 80s and all 90-95 ECMs use a bi-directional data flow. A data request stream of a few bytes is sent from the scanning device. The ECM then replies with a single stream that includes all the data. The scanning device then repeats the request and the ECM replies. This happens many times a second and the result appears to be continuous data. Bi-directional data is usually on pin M.
Assuming you built a RS232 to ALDL cable, you must use the two transistor diagram, not the single transistor diagram. The single transistor cable will work with the first version, but is not bi-directional and won't work with the second. Of course a clue to your design will be if there is a wire on both transmit and receive pins of your RS232 connector.
Also my notes show that the 10K resistor is still needed on the 87-88 ECM. GM was kinda stupid on a lot of what they did scanning wise on the early ECM/10K resistors and this appears to be a relic of the old design. In the 90s GM dropped the need for the 10K resistor totally.
Note - this picture doesn't show it, but the Fiero ECM needs the 10K resistor on pin B. This picture was from a GMC Syclone website
[This message has been edited by phonedawgz (edited 01-21-2017).]
TunerPro RT with the .adx modified for the Fiero ECM. TunerPro RT along with the Fiero $48 adx is the only way that I know of to scan it with a laptop. I modified the $48 to fit the Fiero data stream output. Not sure why but the $48 adx that was out there was two bytes off from the Fiero stream. Testing I used my ALDL cable which is USB to TTL, and then a small interface circuit to go from two wire to one wire. Using the RS232 to ALDL circuit should work fine.
Originally posted by phonedawgz: Later 80s and all 90-95 ECMs use a bi-directional data flow. A data request stream of a few bytes is sent from the scanning device. The ECM then replies with a single stream that includes all the data. The scanning device then repeats the request and the ECM replies. This happens many times a second and the result appears to be continuous data. Bi-directional data is usually on pin M.
Nope. 1227748 and others in P4 Family of ECMs and Does Not have this. Like older C3 Family, P4 only updates the data stream ~2x per sec but @ higher bit rate and Pin M for output. see http://www.exatorq.com/ludis_obd1/index.html for P4 # etc.
Slowly, the clarity builds. I had the gear built and computer working on Sat. I added a 10k pullup resistor to the collector of Q1 on the two transistor diagram.. that allows the computer to talk to itself, getting a response back when not connected to the car. When I connected the data line to the car, the computer would no longer recognize it's cable as being connected, and no joy ensued. The TunerPro RT is acting as the master.. issuing a message, expecting a response, which is called half duplex. Per Ogre, the 1227748 is just issuing data (at 8192) which is called simplex, with ECM as master. So now I have a puzzle.. what software can be expected to work with simplex 8192 messages? All because I want to keep my '87 4 banger working.. go ahead, talk me into a swap.. it won't take much.
Many RS232 to USB won't work w/ non standard bit rate like GM C3 and P4 ECMs uses. Many Com ports on laptops etc are no better. Is a problem cause by chips used in them. This is a very old problem.
Even when they work... needs proper setting for 3 pin connection or wire to jump others to see signal on data in etc. I made RS232 cables years ago but can't remember just which pin jump to others. Maybe 1-4-6 and 7-8 for 9 pin.
After a bunch of work I finally got TunerPro to talk to the 1227748 ECM!
I used a modified $48.xdf and a modified A027.adx. I was able to completely break down the data stream.
I've also found 4 bins online; ACMF (4cyl auto), ALWM (4cyl auto), ATBT (4cyl 5-speed), ATCA (4cyl auto). I am not sure if there are more.
I had to send this code at 8192 baud:
code:
0xF4 0x56 0x01 0xB5
Then I had to listen at 8192 baud:
code:
Header: 0xF4 0x95 0x01 Timeout: 12,000 ms Body Size: 67
I put these in a macro so it sends/listens repeatedly.
In addition, I've created 2 watchlists; one for all data, and one for just error codes. I also created 2 dashboards that can be used and reconfigured as needed.
