Write-Up: Build Your Own (ALDL) OBDI Scan Tool for '95

I'm psyched that it's free. If it works well, I would totally drop the cash to get the registered ver.

I actually bought an OBD2 to USB cable last year specifically for this project. I put it off for a while since I didn't need to scan anything just yet.

I'm going to most likely hack off the USB end, and pin it out to the TTL.

If it works, I'll be in it for a total of like 25 bucks.

Oh yeah, my cable idea worked!

1. Buy an OBD2 to USB cable. I bought this cheapo one, pretty good quality, I just wanted the OBD connector with convenient solder pad pinout. (This is optional, if you want to stick the bare wires into your OBD connector, you can do that too. I preferred to have the connector (don't want to short out your DLC). Buy it here: http://www.amazon.com/OBD2-Diagnostic-Cable-KKL409-1-VAG-COM/dp/B002WIN8VQ



2. Purchase an OSEPP FTDI (FTD-01) Breakout Board. (Must be FTDI FT232RL chip). This particular board allows to switch between 3.3V or 5V. You will want to use 5V for this purpose. I picked mine up from Fry's Electronics for 16.99. You can also get them online at various places. i.e. http://www.amazon.com/OSEPP-Breakout-Board-Arduino-Compatible/dp/B007JBSSGQ



3. Open up the OBD2 to USB cable (4 precision-screwdriver Philips heads)



4. Separate the circuit board from the OBD2 port header. I bent it back and forth until the metal tabs broke. You can use a wire cutter, or whatever.



5. This is what the back of mine looked like afterwards. You'll want to remove those metal pin headers in the center. Snip them with a wire cutter or you can desolder them, whatever works best for you. Don't let them or the solder pads touch.



6. Here's what you should end up with after the modifications.



7. A little pic of the setup I'm using. Nothing fancy. Soldering iron, solder, screwdriver, and a wire stripper/cutter.



8. I cut the USB end off of the cable, and stripped off the rubber and wire shielding. You only need three wires for this to work. There are four inside the cable loom. I eliminated the red wire. I tied the green and white wires together and soldered them to pin #9 on the OBD2 connector. The reason for this is that the ALDL data stream is active on pin 9. Both data transmit and receive go through there. Ground (black wire) goes to Pin #5 on the OBD2 connector.



9. Solder the white and green wires to TXD and RXD. It doesn't matter which wire goes on what pad, it's a closed loop. The black ground wire gets soldered to the ground pad (GND) on the FTDI breakout board. You can use any of the headers. I chose this side out of convenience.



10. Also get some solder on the bottom pads to make sure you get a nice consistent connection. Snip off any excess wire when done.



11. Here's what I ended up with as a final product. It could always look better, but it worked for me.



Total cost was 26 bucks, only took about an hour. You'll also need a microUSB cable. You should be able to get one real cheap.

The kind on the left in this picture:

Drivers will need to be installed before using: http://osepp.com/learning-centre/start-here/ftdi-breakout-board/ftdi-breakout-board-2/

The FTDI board is a TTL (transistor to transistor logic) to USB converter.

Normally TTL would work with RS232 serial ports. But, most newer PCs no longer have serial connectors, and the newer tuning software would also have an issue running on older computers.

So basically this does the same thing as those, just using USB.

By connecting the TX and RX pads together to pin 9 on your OBD connector (and ground), you're allowing the FTDI chip to transmit and receive data from the car.

You can download TunerPro RT here: http://www.tunerpro.net/downloadApp.htm

I used the following definition files for my PCM (16183247)

http://www.tunerpro.net/download/bindefs/GM/5B_TPV5.xdf
http://www.tunerpro.net/download/datastreams/GM/5B_V5.adx

Check out this tutorial on how to use Tunerpro. http://www.gearhead-efi.com/Fuel-Injection/showthread.php?466-TunerPro-starter-Tutorial!-New-users-this-is-a-must-read!-%29

Here's some neat screenshots I took of the Riv scan from last night.

You just had to post this right after I got paid................

Haha, good thing it's cheap, right?

New to the forum and could use some help. I have new to me 95 Riv, and I would like to pull trouble codes before I remove the engine ( doing an engine swap into a Fiero). I've had some experience with Tunerpro, having done a TPI install in my Le Camino. I have Tunerpro RT, and a 12 pin ALDL cable. I have downloaded the BIN, XDF and ADX files. I found on another forum a picture that showed a way to connect my ALDL cable to the 16 pin OBDII connector, and I have tried that with some success. Let me know if this is wrong.


I do get connection, but no data flow. I think it may have to do with the setup in the Acquision definition, and I've gone in and tried to edit it, but can't seem to get the data flow working. I send Mode 8 (Disable Comms) Send macro for the connection command, and then send Mode 1 Message 0 (Data) send for the monitor command. This will get me connected, but no flow. If I change the Monitor command to Mode 8 ( Disable Comms) Send, then it looks like I am getting some data flow, but all errors. No data shows up on the tables or on the Dashboard.

Any ideas on where I might go from here?