Uber-easy DIY USB ALDL Cable

[kunsan1987]

Here is the one i bought from amazon.i have not been able to try it with an ECM yet but it talks to my garmin gps.

http://www.amazon.com/UART-Module-Se...=pd_ys_iyr_img

[RobertISaar]

the pins necessary are present, however it's a CP2102 IC, which isn't quite as capable as the FT232RL, so it MAY work, but i wouldn't gaurantee it.

[one92rs]

ok so this can be used to make a cable that will datalog for cheaper than the 59 bucks for a cable. i am not an electrical genious here. can someone show me how to make it aor what all i need to make it work. a diagram of sort.

[RobertISaar]

with the one i posted:

connect the RXD and TXD pins together(solder would be my method), then connect that circuit to the ALDL pin M, then connect the ground pin on the converter to the ground pin in the ALDL connector (pin A).

it's that simple.

[one92rs]

i will get a buddy of mine to look at this tomorrow. he is all about electric. he is trying to set up a miata with a/c drive motors right now. thanks buddy.

[EagleMark]

with the one i posted:

connect the RXD and TXD pins together(solder would be my method), then connect that circuit to the ALDL pin M, then connect the ground pin on the converter to the ground pin in the ALDL connector (pin A).

it's that simple.

To easy! Does it work? Still to easy... and to cheap...

[RobertISaar]

i've been using it to troubleshoot my testbench. i seem to get quite a few packet errors on the bench if i don't have my 4K PPM signal hooked up to anything though. if i either connect it to a spare cluster or directly to ground, problem goes away ~99%.

however, when i had it hooked up in-car, i had 0 packet errors, so it must be something about the bench causing it.

[phonedawgz]

USB to ALDL 160 Baud Pin E or 8192 Baud Pin M cable for $55 shipped -

http://www.reddevilriver.com/aldl.html

It does use the FT232RL chip

By the time you do $10-15 for the FT232RT USB, 20.90 for the OBD1 ALDL cable shipped, $5 for the box you are at $40. The pre-built cable is $50 + $5 shipping.

[belaw]

with the one i posted:

connect the RXD and TXD pins together(solder would be my method), then connect that circuit to the ALDL pin M, then connect the ground pin on the converter to the ground pin in the ALDL connector (pin A).

it's that simple.

What do you do with pin B on the ALDL connector?

[phonedawgz]

Earlier OBD1 vehicles need a 10K resistor between pins A and B to start the data flow.

Later OBD1 use bi-directional data flow on pin M and don't require it. Having the 10K resistor between pins A & B won't hurt however.

[89S10_Project]

Earlier OBD1 vehicles need a 10K resistor between pins A and B to start the data flow.

Later OBD1 use bi-directional data flow on pin M and don't require it. Having the 10K resistor between pins A & B won't hurt however.

Is it possible that my 1989 S10 needs this 10K resistor present and that's why I'm not getting data?

[RobertISaar]

depends on the application. most cars don't need it, the some that do tend to need a 10K resistor connected from the B pin to the A pin(or the ground on the converter) either temporarily or permanantly.

if you use a male OBD1 connector, then you could simply run a wire from the B pin to a rocker/toggle switch, then to a 10K resistor, then to the ground circuit. you can then hide all of it in a small project box from radioshack. i think i use the 3" X 2" X 1" versions.

Having the 10K resistor between pins A & B won't hurt however.

depends. some applications go into "ALDL mode" and will change the idle speed and add up to 10* of spark advance.

[belaw]

depends on the application. most cars don't need it, the some that do tend to need a 10K resistor connected from the B pin to the A pin(or the ground on the converter) either temporarily or permanantly.

if you use a male OBD1 connector, then you could simply run a wire from the B pin to a rocker/toggle switch, then to a 10K resistor, then to the ground circuit. you can then hide all of it in a small project box from radioshack. i think i use the 3" X 2" X 1" versions.



depends. some applications go into "ALDL mode" and will change the idle speed and add up to 10* of spark advance.

This is for a '7427 PCM and I will probably omit the ALDL connector for a permanent install. So can I just de-pin the white/black wire that terminates at pin B from the PCM and pitch it?

[DownUnder]

with the one i posted:

connect the RXD and TXD pins together(solder would be my method), then connect that circuit to the ALDL pin M, then connect the ground pin on the converter to the ground pin in the ALDL connector (pin A).

it's that simple.

Just to confirm the unbelievable simplicity to making this aldl cable, Hopefully a small image with red circles will help anyone else with the same question!
aldlcircuit.jpg
Solder the Rxd and Txd together, solder single wire from that to communication pin on Diagnostic plug.
Then solder wire from Gnd to ground pin on plug.
And obviously keep the bridge over VCC and 5V or solder together if intending to keep it like that.
That about cover it for 8192 baud communication?

Still cant believe aldl cable can be made for ~$20!. Paid $80 for my last one!

[RobertISaar]

yeah, unless you need the 10K resistor for the applications that need them. in which case, you will need to be able to switch that circuit through the resistor to ground and off again.