$7 USB ALDL cable

[pitzel]

Okay everyone, as a public service, I thought I'd do a bit of a write-up on how hooked up to my 1992 LH0-engined car with a <$8 USB cable and no messing around with MAX232's, transistors, resistors, or even soldering.

 

Step #1:

 

http://www.aliexpress.com/item/Free-Shipping-FTDI-5V-USB-to-TTL-Serial-Cable-Adapter-FTDI-Chipset-FT232-cable-Computer-Cable/714542272.html

 

Buy that. $7.66 with free shipping.

 

(must be this one, with the FTDI chip to support 8192 baud, and must use 5V TTL levels. Many Arduino-targeted cables use 3.3V, which may not be adequate for the TX pin to the 5V logic used in the ECU!)

 

Step #2.

 

Wire the TXD and RXD pins together, Green and Yellow.

 

Step #3.

 

Wire the combined TXD and RXD pins to the "M" connector on the ALDL block

 

Step #4:

 

Wire the Black connector (GND) to the "A" connector on the ALDL block.

 

Step #5:

 

Connect USB to laptop, let Windows install the FTDI drivers.

 

Step #6:

 

Download freescan from: http://sourceforge.net/projects/freescan/ , and install.

 

Step #7:

 

Select the appropriate COM port (showed up as COM4 for my laptop), and select "GM 410B" as the ECU in the software. Also, make sure you select "Interact" mode.

 

Step #8:

 

Set e-brake (to inhibit DRL's draining your battery and just as basic protection since you'll probably wanna sit in the passenger seat to mess with a laptop), turn key to run position. Look at the LEDs on the USB connector, to make sure there's some data flow. If not, then you've done something wrong earlier.

 

Alternatively, use a terminal emulator such as PuTTY, set into serial mode, with the appropriate (virtual) com port (mine was COM4), and the baud rate set to 8192. You should get at least a partial data flow when the key is in the RUN position.

 

Step #9:

 

Press "Force Data" button in Freescan screen if data does not transmit automatically.

 

Step #10: Start engine to get some more meaningful data, but you should be getting data flow just from being in "RUN" and trying the "Force Data" function.

 

 

Disclaimer: This worked on my 1992 LH0-engined car. It may not work on other cars. But this proves that an ALDL-interface cable can be built for $7.66 including shipping.

 

 

Extra credit: For an additional $5, order: http://www.aliexpress.com/item/OBD-2-16pin-OBD1-OBD2-to-GM-12Pin-Automobile-diagnosis-scanner-Adapter-Connector-Cable-for-GM/539541218.html . Cut off the other side of it, and connect to your $7.66 USB to ALDL adapter. Make everything neat with heat-shrink tubing.

Edited July 30, 2014 by pitzel

[RobertISaar]

you'll need to be VERY careful about the ALDL ends, a lot of them aren't wired with all 12 pins(most seem to be 4) and they tend to not have the important ones present. the last 10 or so i've gotten have that problem and now i'm trying to work out a deal with someone that does plastic injection to make a custom connector.

 

EDIT: didn't see they listed a diagram on the site, A and M are present which covers every W-body, but B and E are not, which would cause issues with a lot of other applications.

Edited July 29, 2014 by RobertISaar

[pitzel]

Yeah, I have no idea if this setup would even work with the old 160 baud stuff even if wired appropriately. Anyways, I've been reading a few of the other threads, and it seems that there's people who want to put a resistor and a diode into such a setup. I've racked my brain a few times asking "why", and can't figure it out . Is there something major I'm missing here?

 

 

 

err: found your post at http://www.gearhead-efi.com/Fuel-Injection/showthread.php?719-Uber-easy-DIY-USB-ALDL-Cable ; clears up a lot of my questions about Tunerpro, lol. Thanks!

Edited July 30, 2014 by pitzel

[RobertISaar]

they work with the 160 streams if the ALDL connector has the pins necessary(always need E, some need . some of the older stuff also operates at system voltage(~12-14V) instead of the 5V used on later applications. i want to say a 5.1V zener is the fix for that.

 

i can see why some people would put in a resistor and diode to isolate the Tx and Rx lines, but i've found it to be completely unnecessary as well.

 

i don't use the converter you list because i've had bad luck with them in the past.... with it sticking out of the USB port as far as it does combined with weight, the USB connector became intermittently bad and eventually the board quit working completely. at that point, i went to the different board design that has just a normal USB cable at the computer and locates all of the sensitive stuff in its own enclosure.

 

 

 

granted, i'm probably a lot rougher on equipment(and use it more often) than most people, but that scares me away from that design.

[pitzel]

What is the price of this usb?

 

Click the link, and it will give you the latest price.