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An ECU scan tool for turbo and NA owners

Posted: Sun Apr 25, 2004 5:00 am
by vrg3
I got frustrated by my Select Monitor not being backlit so I decided I'd use my laptop instead. I wrote a little scan tool that lets you monitor what the ECU's thinking much like the Select Monitor does. The coolest part is the custom hardware required: it's just 3 wires! You do need an IBM-compatible laptop with a parallel port though.

Update: It should now support non-turbo models too! Give it a try, everyone! :D

Update again: Supports serial ports with a little more hardware now too.

Posted: Sun Apr 25, 2004 5:07 am
AWESOME! I assume this will also work for non-turbo ecu's? Did you ever figure out how to get it to display more than one value at a time? Or will it do this already? I might have to make this :)

Posted: Sun Apr 25, 2004 5:12 am
by vrg3
Thanks. :)
I assume this will also work for non-turbo ecu's?
No, not yet. See below.
Did you ever figure out how to get it to display more than one value at a time?
You can't read more than one parameters at a time. You can in principle quickly alternate between different parameters. However, this is a bare-bones program for two reasons: It does asynchronous communication using bit-banging so there isn't a whole lot of spare processing to go around, and I wrote it in assembly language, which I am quite out of practice working in.

Non-turbo owners: If you would like to help me make a version of this software for you, build the interface and download the software. It won't do anything with your ECU except tell you the ROM ID. Get it to do this, and then email me your ROM ID, the model year of your Legacy, whether it's a standard or an automatic, and (if possible) the part number from the sticker of your ECU. If I can collect enough data points I should be able to make a non-turbo version.

Posted: Sun Apr 25, 2004 5:16 am
Alright, I might head down to radio shack and see if they carry the parrallel port, if so we're in business :) I dont think I can get the part number from MY sticker, but I should be having another 90 at ecu sent here soon I assume the part number is the same, or did you mean serial number?

Posted: Sun Apr 25, 2004 5:20 am
by vrg3
Well, I know what the part numbers in general are, and they're not all the same even for a given type of car, since there are different revisions.

For example, there were four original ECU part numbers used on automatic models in 1990: 22611AA560 through 22611AA563. Each, I would expect, has a different ROM ID and potentially has to be treated differently.

I was just hoping to be able to correlate part numbers with ROM IDs. I understand it's hard to get at your ECU's part number, though, which is why I said "if possible."

Posted: Sun Apr 25, 2004 5:21 am
actually here's a picture of that stuff from the auction: Image

Will that work? :D

Posted: Sun Apr 25, 2004 5:22 am
heh I see, well I'll go try and check my ecu right now, I actually dont think it'll be too hard to see since I know where that lil green led is. :D

Posted: Sun Apr 25, 2004 5:22 am
by vrg3
If you hook that ECU up to your car and get me its ROM ID, it'd help. :)

Posted: Sun Apr 25, 2004 5:41 am
yes yes, but I can't do it right now. anyway the numbers I've got are 22611 AA381 for the part number, the bottom left is AA11-000 R82 and the bottom right is 9522 I'll see if I can get the parts to make this tomorrow :)

Posted: Sun Apr 25, 2004 6:55 am
by legacy92ej22t
:twisted: Hell ya, Vikash! That's sweet. Now if I only had a laptop. Lol

Posted: Sun Apr 25, 2004 7:00 am
by vrg3
Save up a little and pick one up on eBay. You can get an early Libretto as cheap as $100. Librettos are awesome; they're about the size of a VHS tape but are actual fully functional laptop computers. I love mine.

Posted: Sun Apr 25, 2004 7:11 am
by legacy92ej22t
Really, that sounds sweet. Eventually I'd like to get a nice laptop for internet, watching DVD's , games ect... But it'd be cool to have something small and cheap just for the car.

Posted: Sun Apr 25, 2004 12:19 pm
by mikec
I can't wait to try this Vikash! I'll see if I can get this tested later today, and I'll post my results.

Posted: Sun Apr 25, 2004 4:04 pm
by vrg3
Thanks, Mike, that'd be great!

Posted: Sun Apr 25, 2004 6:07 pm
by TheShocker
With some more work can you say datalogger?

Posted: Sun Apr 25, 2004 6:16 pm
by vrg3
This hardware is a bit too simple for a useful datalogger. I have my own ghetto custom datalogger based on a slightly more complex interface that uses a serial port, but even then the sample rate isn't very high and only one parameter can be sampled at a time. Those last two are limitations of the ECU.

Posted: Sun Apr 25, 2004 7:13 pm
by Legacy777
this is sweet!!!

I should try and get a connector so I can easily plug in and out of it.

I'll have to try and get the connectors and stuff.

Posted: Sun Apr 25, 2004 7:25 pm
by vrg3
Cool! I'd love to have you and THAWA test the non-turbo version.

You understand, though, Josh, that this in the end will be about the same as the Select Monitor except for 3 things: it won't deal with trouble codes (those are easy to deal with using the black and green connectors anyway), it will be on a computer screen, and it will update several times faster.

Any 93-94 non-turbo owners wanna help?

Posted: Mon Apr 26, 2004 3:50 am
You said the other pins in the yellow connector are for the other on board computers right? Do you know where they connect to the db25 pins?

Posted: Mon Apr 26, 2004 3:58 am
by vrg3
The PC's parallel port doesn't correspond at all to the car's diagnostic port. I just picked a configuration that would be simple to hook up for ECU diagnosis.

I don't have any knowledge about how the other computers (TCU, cruise, air suspension, etc) communicate with the Select Monitor so I can't say how you might connect them to a laptop computer.

Posted: Mon Apr 26, 2004 4:19 am
by BAC5.2
Vikash - I will be trying to set this up this weekend. I had a few questions though...

1) Can this be left plugged in for an extended period of time? I'd like to have a co-pilot checking and reading me numbers while driving to see if any red flags are thrown.

2) I see that you can connect the yellow connector to a Stereo adapter you mentioned. How do you attach it to the computer though? Just stick it into the parallel port holes? Or is there an easy way to tap the wires into a male parallel port so I have a more secure connection?

3) Do you plan on advancing the program any? Perhaps a graphical interface with more than one parameter being displayed at once?

Posted: Mon Apr 26, 2004 4:27 am
by vrg3
1) Yes. There should be no problem leaving it plugged in until the end of time :). I highly recommend having a codriver operate the computer; splitting your attention between the road and a keyboard is not a great idea.

2) Your local Radio Shack should have a couple of different types of DB25 male connectors and hoods to go on them. If you don't want to solder, they have one where you can just crimp pins onto the ends of wires and insert the wires in the connector housing.

Or you could hack a printer cable in half.

3) Realize that I've only spent a couple of hours on this. The first advancement I'd like to do is make it work on other BC/BFs. If I do decide to make a more sophisticated version with some graphics and multiple parameters, though, it probably won't use this simple hardware interface, since this one requires a lot of CPU attention to operate (kind of like WinModems vs. real modems).

Posted: Mon Apr 26, 2004 4:40 am
by BAC5.2
Ahh, I gotcha. The only way I'd look at it without a co-driver is if it was graphical and on a screen like the HKS CAMP setup (which is uber pimp).

Looks like I'll be doing this this weekend!

Posted: Mon Apr 26, 2004 6:30 pm
by DLC

Best Buy has a Subaru install kit for $17. Dashworks 99-8900.

Circuit City has a Metra kit also, model MET 808901. $17.

Posted: Mon Apr 26, 2004 9:07 pm
by BAC5.2
Which one is better Dave? I guess neither really, since it's just a peice of plastic with wires on it...