Trying to communicate with 1226865 ECM

American Delco GM ECUs and PCMs, ALDL, OBD 1.5.
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Re: Trying to communicate with 1226865 ECM

Postby delcowizzid » Sun Sep 15, 2019 12:39 pm

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Re: Trying to communicate with 1226865 ECM

Postby delcowizzid » Sun Sep 15, 2019 1:24 pm

That pick is also looking into the db9 port on the pc just in case you built it thinking it was the plug end
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Re: Trying to communicate with 1226865 ECM

Postby ndndndnd » Sun Sep 15, 2019 6:16 pm

Hi Delco, thanks for the information!

R4 - the 1.5kohm resistor? I did try with and without that, but with no success.

I notice on the WinALDL layout you've posted there's no R2 10kohm resistor between Pins 4 (5V) and the RxD line? I was under the impression this was necessary to switch the transistor? Nonetheless I've tried with and without that resistor and without success either.

I'm using 2N3904 resistor, which I guess I chose at random - I don't know what the differences are between those resistors.

I have measured voltage at Pin D, which oscillates between about 7V and 9-11V on my DVM with pins A and B bridged with a 10kohm resistor. I'm assuming this means the port is working and data is flowing!

My laptop doesn't have a serial port - hence using the FT232 to transmit the data via USB.

Cheers,

ND

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Re: Trying to communicate with 1226865 ECM

Postby delcowizzid » Sun Sep 15, 2019 6:22 pm

The resistor from pin 4 to pin 2 is 12v power supply but some serial ports don't have enough so it gets 12v from the car instead the transistor is switching that 12v to earth making it go on and off on and off into the serial port rx pin its just inverting the signal
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Re: Trying to communicate with 1226865 ECM

Postby delcowizzid » Sun Sep 15, 2019 6:30 pm

Does the ecu have a removable memcal if so look for the BCC its a 4 letter and 4 number code I'll see if I can find a file that suits for tunerpro
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Re: Trying to communicate with 1226865 ECM

Postby j_ds_au » Mon Sep 16, 2019 9:10 am

Hi ND.

Your circuit as is looks OK (although your soldering doesn't). Don't omit resistors and don't substitute with a zener. And yes, a genuine FT232RL can handle the oddball 160 baud data stream. What you need is the correct FTDI software to configure the chip to invert the RX line. If the software you have only detects FT232BM (which is not actually obsolete, just renamed FT232BL in its lead-free guise, but lacks the inversion feature anyway), then you have the wrong software.

Also, I don't want to be anal guys, but ... please know that the 9-pin D-sub connector isn't a DB9, that's an Aston Martin car, not a connector. That second letter tells you the size of the connector shell/body (in this case, it's E). If you don't know the correct letter to use, you can simply omit it, so D9 would be perfectly fine.

Joe.
Last edited by j_ds_au on Tue Sep 17, 2019 7:19 am, edited 2 times in total.

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Re: Trying to communicate with 1226865 ECM

Postby antus » Mon Sep 16, 2019 9:55 am

Just to add to the oscilloscope options too, something like a hantek usb scope is good bang for buck because you can get a nice larger UI on the computer screen, but at a minimum something like this would at least give you eyes on the signals. https://www.ebay.com.au/itm/Soldered-DS ... 3515265070
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Re: Trying to communicate with 1226865 ECM

Postby ndndndnd » Tue Sep 17, 2019 11:33 pm

delcowizzid wrote:Does the ecu have a removable memcal if so look for the BCC its a 4 letter and 4 number code I'll see if I can find a file that suits for tunerpro


I can't see a BCC code anywhere? The ECM is a 1226865, and the EPROM is 16044302, PROM ID 4303. Does that mean anything? I have looked for XDF files etc for this ECM and couldn't find anything, so it would be great if you could point me in the right direction.

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Re: Trying to communicate with 1226865 ECM

Postby ndndndnd » Tue Sep 17, 2019 11:44 pm

j_ds_au wrote:Hi ND.

Your circuit as is looks OK (although your soldering doesn't). Don't omit resistors and don't substitute with a zener. And yes, a genuine FT232RL can handle the oddball 160 baud data stream. What you need is the correct FTDI software to configure the chip to invert the RX line. If the software you have only detects FT232BM (which is not actually obsolete, just renamed FT232BL in its lead-free guise, but lacks the inversion feature anyway), then you have the wrong software.

Also, I don't want to be anal guys, but ... please know that the 9-pin D-sub connector isn't a DB9, that's an Aston Martin car, not a connector. That second letter tells you the size of the connector shell/body (in this case, it's E). If you don't know the correct letter to use, you can simply omit it, so D9 would be perfectly fine.

Joe.


Thanks for confirming the circuit's ok and confirming my query about the Zener diode. You are quite right to criticise my soldering - I am less than experienced at it! But hopefully it should be ok for an electrical signal...?

By saying the FT232RL can handle the 160 baud data, do you also mean at 12V?

Can you show me what software to use? I've used FT_PROG from the FTDI website, and that identified the chip as an FT232/245BM and that I needed to use older software. I also downloaded MPROG, which is the older software, but this seemed to depend on you telling it what you have. I've confirmed the chip works (?) using puTTY, and also downloaded something called 'chipgenius', which seemed to confirm it's FTDI, but wouldn't say what chip it is.

FT_PROG gives the device out put as just rows of FFFF FFFF FFFF FFFF etc....

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Re: Trying to communicate with 1226865 ECM

Postby ndndndnd » Tue Sep 17, 2019 11:45 pm

antus wrote:Just to add to the oscilloscope options too, something like a hantek usb scope is good bang for buck because you can get a nice larger UI on the computer screen, but at a minimum something like this would at least give you eyes on the signals. https://www.ebay.com.au/itm/Soldered-DS ... 3515265070


I didn't know you could pick them up so cheaply! I'll look into the UK-available equivalents and see if I can find something.

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