I thought it may get more traffic over here rather than the PCM tuning section as it's LT1 specific.

So I have sold hundreds of these and the demand has dropped off so I decided to show you all how to make your own USB programming cable. These can be built for less than $10 total.

All you need is a USB to serial adapter with a FTDI chip on it and a 1000 ohm resistor and a simple glass diode. The USB to serial adapter can be had on ebay. The resistor and diode can be bought at radio shack for cheap.

The build and testing directions are in the vid but I will repeat them here.

Solder the resistor to the diode end without the black stripe. Solder the other end of the resistor to the RX terminal on the USB adapter. Solder the diode other end with the black stripe to the TX terminal in the USB adapter.

Then connect the adapter ground terminal to your car obd port black wire. Connect the resistor/diode to the tan wire on your obd port. It will work with either square and obd2 style port. Just look at the back of the port for wire colors.

Here is a link to the build and test video using data master data logging software.


Enjoy !

 

MY skills in something like this suck, but would be interested in buying one. How much do you charge for them?

 

I like that. Would you mind sharing any info on the wall wart setup to power the PCM? I made a really ghetto one years ago but it only worked a few times before it burned up.

 

http://www.gmassie.net/13secss/benchtop.pdf

Just connect the power as shown here and the benchtop harness ground and data wires to the USB adapter.

I just found a 12 volt wall wart that outs out at least 500 mA. The PCM does not draw much current while just sitting there.

 

Yeah I would be totally interested in this as well. I am not very good at arts and crafts

 

Is there any reason this cable will not work?
http://www.gearbest.com/development-.../pp_54471.html

You still need the resistor and diode, I'm sure, but this looks like the cheapest way to go

 

That cable is probably designed for 5v or 3.3v.
A lot of newer electronics are like this, and the only difference for them is the voltages the "serial" operates at.
The old serial (RS-232 IIRC)was designed for about -13 - +13v.
It may work, work wrong, or just burn up.

 

With what I said before I think this adapter will work

Part# USB-RS232-WE-1800-BT_0.0 found on http://www.ftdichip.com/Products/Cables/USBRS232.htm

 

Does GM ODBI or ALDL on a 94 F-body operate at +/- 13V?

 

I am fairly sure it does.
One time I was trying to make my own cable. I got frustrated I ended up just running the data line into the into the serial port and the computer was able to read the line, but not send anything. This was an old crappy laptop with both a serial and parallel port.

 

12445

 

Tunercat, TunerPro programming software.
Datamaster and PCM Comm for datalogging

 

AKNOVAMAN

Have a part number for the diode? Have the 1K resistor.

Thanks

 

Bringing this back. Does anyone know what the diode is that is needed? Another writeup that I saw did not show this or the resistor as needed. I have everything except the diode.

 

any General Purpose diode series 1N4001 to 1N4007 will be ok

 

I made my own and didn't use the resistor or diode. In fact it wouldn't work with them on the circuit.

 

This doesn't work with 1993 cars I'm assuming?

 

I believe that the 93 cars were a chip that needed to be swapped out and programed. 94-95 are the only ones that this will work for.

 

The YouTube video is no longer available, bumping for an update if possible

 

not sure what was in the video, but here's how i built my cable.
I didn't use a diode or resistor.
i bought one of these:

http://www.ebay.com/itm/FT232RL-USB-...8AAOSwI59aTGDT

and one of these:
http://www.ebay.com/itm/GM-12-Pin-OB...8AAOSwkLhaAvGZ

and I cut the cable and soldered the tx/rx pins together and to the cable.
i soldered the ground pin to the cable.

you will need to verify which wires in the cable are correct using a multimeter or test light.



complete cable


been using it to scan and program for years without issue.