Interfacing with the ECU

**SuperMatty** · 04-30-2002, 01:31 AM

Hey Aaron or anyone else,
Have you ever messed with the powertrain control module on your car? According to my 1997 Chevrolet Malibu's wiring diagrams, the automatic transmission shifting is controlled by all of the on/off combinations of 2 solenoids; corresponding to 1, 2, 3 and overdrive. It appears the input signal to these 2 solenoids is attached to the diagnostic port under the dash; pins 11 and 17 I think. Could it be possible then, if I grounded pins 11 and 17 according to the way I want the automatic transmission to shift, that I could make my car shift tiptronically?

Just wondering if anyone else has tried this. I got ahold of Mitchell's On-Demand 2002 software. It has all the technical information on import and domestic cars from 1983 - 2002 you could ever want.

**Aaron Cake** · 04-30-2002, 08:37 AM

I haven't done anything like that...The RX-7 ECU is very primitive, and most people replace it if they get into any serious modding...

Sorry, can't help.

I know there are some past threads on this, but I don't know how much info they contain...

**Rob** · 04-30-2002, 09:58 AM

I think Ashley Powers interfaced his ECU to his PC, but that was only to read engine info, might be a starter for ten.

Rob

**LoreleiGuy** · 04-30-2002, 10:50 AM

You might want to look up OBD-II. That's the On Board Diagnostics that post 1995 cars have. I know there's at least one company selling OBD-II -> serial adapters, but I do not know if they are both read and write.

**GMJArts** · 04-30-2002, 02:23 PM

This can be done very easly.
I currently do it with my 94 Trans Am, which is a OBD 1 Car. So Software is Free and easy to come by. I just have a ALDL Cable pluged into my cars Diagnostic Port under the dash. And it is interfaced with my Laptop. I also have specialty software that will let me mod. any of the settings on the onboard computer for racing and tuning reasons.

For most of you, I think that it would be a waste. I have invested lots of money and lots of down time from screwing **** up from doing this, one wrong move and your onboard GM PCM is dead. I am my thrid PCM, which has lots of features in it so that I can not **** it up. It is cool for me to have these features in my car do to the mass amount of modafications that i have done.

Just my $.02 on the subject, but if you have a 96 and newer car check out www.autotap.com, they make systems for GM, Ford, Chrysler, And Import cars, These are all serial based systems that interface with your cars PCM (ECU). ATap will only do diagnostics, there is no tuning with that system, that is the standard for personal use diagnostics.

~Gary

**SuperMatty** · 04-30-2002, 06:08 PM

So GMJArts, are you saying you control your shifting via the laptop then? If so, is what I'm saying correct? Can it be done without software?
You gave a link to the autotap software, but like I stated in my original post, I'm looking to control when the automatic transmission shifts, not just obtain measurements.

**GMJArts** · 04-30-2002, 11:43 PM

What kind of car do you have, I only know of a few high performace cars that have direct conection software to make these changes without the use of like a hex editer.

Late Model GM's, Mustangs. That is about all I in know of.

~Gary

**SuperMatty** · 04-30-2002, 11:53 PM

I have a 1997 Chevrolet Malibu. I"m not sure you know what i'im asking. I want to control my transmission shifts on the fly, like an F1 transmission, with the press of a button. Not change at what point that the computer shifts automatically. I also want to do this without software.

Seeing the diagram of my car's wiring show me that solenoids A and B control the transmission shifts, made me think it might be as simple as varying whether or not pin 11 and 17 are connected to ground or not.

**Fosgate** · 05-01-2002, 01:45 AM

Originally posted by SuperMatty
Just wondering if anyone else has tried this. I got ahold of Mitchell's On-Demand 2002 software. It has all the technical information on import and domestic cars from 1983 - 2002 you could ever want.

I havn't done anything like this but im planing to... If you could help me that is

Well as you said you got this software "Mitchell's On-Demand 2002"... does it have any info on Mazda 323 GT/GTX/GTR or Ford Laser TX3, Ford Capri Turbo? 86-89 model is what im after...
I had a long post one one of the forums talking about this topic.
Search for "Mp3car to control your car".