Pontiac GTO vs GM ECMs

Just a heads up to you folks like me that have a GTO engine. The green GTO connector which is the equivalent to the GM Red connector does not fit into the GM ECM. It can be modified to fit, and I may do that, after I check the pinouts, removing the guides should make it fit. The Camaro ECM I have has all the FAN and A/C functions I wanted. I have read that I can flash the GTO ECM with a Camaro tune, I have HPTuners, and will look into that. I will let you all know how this works out.

Did you not get the GTO ECM with the engine? That would have worked just as well. I am actually using an ECM from a '04 Chevy Astro van (SERV NO: 12586243 HDW NO: 12583659) that has the abilities to do throttle by cable. The guy who flashed it for me flashed a '04 GTO tune on it. I just need to add the connectors and wiring for the ICV and TPS and remove the electronic throttle by wire connector and wiring.

Check lt1swap.com. It has a fantastic amount of information, including what's needed for certain swaps and how to make a standalone harness. If I remember right, there is a difference between the old school red and blue ECM and new school blue and green ECM when it comes to O2 wiring as well, so just a heads up on that as well.

As for the Astro van ECMs, I picked mine up for somewhere around 60 shipped. Can't argue that. I still don't know why people are chasing the older LS1 harness and ECM.

I am in that same situation. So are you saying the actual clear green plastic that fits over the connector would have to be modified? I have not tried to fit the GTO harness to the Camaro ECM, yet.

Yep, the guides on the green are different. Blues are OK. If I can flash the GTO with the Camaro tune, no worries, will post results. I don't really care which ECM I use, as I have both, 2002 Camaro/Firebird and 2004 GTO. 2004 GTO did not have drive by wire, or displacement upgrade, I just want my fan and a/c controls!

I can just buy the blue guides or modify the green ones to fit. I already have the Camaro ECM tuned/flashed.

I tried to flash the GTO ECM with a Camaro tune, no go, even though I am licensed. I'm not sure I'd want to do that after doing a compare of the two files. Quite a lot of differences between them, will test this weekend to see if the fans work, then the A/C.

Wait, why are you trying to flash an earlier style ECU bin to a new style one? It doesn't work that way. I don't see what's so desirable with the Camaro/LS1 bins either. The guy who flashed my ECU says that he used a GTO bin/definition file.

If anything, your best resources will be the support through your tuning package. I know HPTuners and EFI-Live have great technical support and will help you out.

The GTO didn't have one of the fan and A/C controls, which is why I was trying a Camaro unit. The body control module of the GTO performed those functions. I added the missing pins to the wiring harness, if the fan sitch and A.C control work, I am good. Otherwise I'm looking for ideas. Thanks,

You don't need either of those controls in the ECU, just let the Porsche fan controller runt the fans and the Porsche ac controller run the ac. It's a lot less wiring to mess with and no ECU head aches.

I know I could have gone that way, but I decided not to, I wanted the GM ECM to control the fans and A/C, and have the flexibility to change settings for the fans with my HPTuners. My radiator does not have a temp bung in it for the Porsche switch, I already have new wiring, relays and circuit breakers for the fans, that work when simulated. Can't seem to find information on whether the GTO ECM has the funtionality I'm looking for, but not programmed in. Thanks,

I contacted a tuner and described what I needed the GTO PCM to do and he said it could not be done, to his knowledge. So, like you I got a F-body PCM. There was a thread on LS1tech.com about this very thing and no one could come up with a solution for the AC control from the PCM.

Thanks Arthropraxis, I couldn't find that thread. Looks like I'll dump the GTO ECM as planned and get a new connector or a later non GTO ECM.

Why do you need or want the ECU to control the AC? It's not necessary..............
As far as the fans, just use an after market thermostat type switch.

I was originally going to use the Porsche A/C and fan system, making the electronic portion of the conversion much easier. It was suggested that as much of the Porsche electronics be omitted as possible. My plan then changed to use the LS computer to control the fans and A/C. What are you doing with the conversions and what would be best for long term reliability?

I want to use the GM ECM to control the A/C so it turns the compressor on and off at certain RPMs, and to adjust idle.

Idle is not really an issue at all. Only thing I could see that might be helpful would be the RPM control .
I just use the factory Porsche clutch wire and tie it to the GM compressor and run a trigger wire to the ECU to let it know that it is on.

That's another problem I have, can't let the GTO ECM know the A/C is on, that trigger wire went to the body control module, stupid Pontiac.

Admin, would the trigger wire be as simple as a spiced wire running back to the ECM? If so, where and what wire do you spice from and what pin on the ECM does it go to? I would think A/C request or clutch control relay.
The GTO may be able to have A/C request programmed in from another vehicle.