LS + MRS Device + BRZ = Almost a working car?
 

This thread is to help document myself trying to get an ls to be as fully integrated into the brz as possible while trying to pass NY inspection.


My current goal is to take a Gen 4 LS (which I pulled from an 06 Envoy), strip the wiring harness down to the bare minimum, use an MRS Device to have the BRZ ECM and LS ECM talk to each other.


My current problem is that I need to know what I should let the BRZ control, and what to have the LS control.


Thoughts:
BRZ Controls things like the fuel pump, radiator fans, Starter?, AC,
LS ECM just keeps the engine running.


Are these thoughts fine? or can I let the LS control the AC, Starter, etc. and the MRS device will let the LS ECM know when the BRZ wants those things on.


I am fine with making brackets to mound brz accessories to the ls and would save on my budget.


This goal of this thread is to document my LS swap while also showing the wiring process and everything that I encounter.

LS ECU will need to control fuel pump, radiator fans, starter, A/C compressor, Alternator. BRZ ECU is only there to keep the CANBUS system intact and does not run anything.

You will need to bypass the fuel controller in the passenger side rear trim panel. You can tap into the fuel pump wiring at the pump, or at the controller. Leave everything else, but you will want to take the power and ground wire coming from the pump and splice the ground to the chassis and power to the Fuel pump power wire in LS ECU.

Same goes for radiator fans, starter, and A/C. A/C will need the compressor trigger wired from GM to the BRZ harness.

Thanks!
I figured I should've let the LS control things like the alternator and fans and such, but I was hoping that I didn't have to splice into those haha. running the compressor trigger wire from gm to brz harness will allow the gm compressor to turn on when the HVAC button is pressed?

Unfortunately doesn't work like that (For the most part). LS ECU needs to control everthing engine related. Including fans/alternator.

Will need to run new fan relays or mess with the factory fuse box as the factory fan controller has three relays and is kind of a mess.

You will need to connect one wire from the gm alternator into the factory harness. This connects the battery light in the dash and tells the alternator when to turn on.

and as for the A/C compressor, Yes. You are correct.

One way to make it easy it to purchase an LS Standalone harness. I have a speartech LS3 harness and it made it easy.

Does the MRS device already have tested A/C working? The main reason why I didn't go for it back a year and a half ago was the lack of AC?

No. He is currently working with a company last I heard. No idea on a time frame, but it's getting there.

@MRS-Colin from MRS is local to me. He'll probably show up in this thread.

Assuming he shows up in here: Colin -- I dont have the original engine in my FRS but if you want to do some testing for A/C, my car's electronics are still in tact and garage is open for you.

Because I'm paranoid about electronics and modularity, I'm sure ill keep the brz harness in the car while I get things sorted out.

Thanks @spitsnaugle for pointing this out to me. I'm still alive and kicking.

Status of the module is that I have verified code for multiple applications using a E38 ECU for cruise control and A/C control. I'm just waiting for a car to integrate all of these features into. I've had some interest from people somewhat local to me, but nothing has come through. We are well over the threshold of modules sold to get this stuff working, I just need a car to do it! I half thought about swapping one myself, but I just don't have the time.

I might take you up on prodding at your car while sitting. I've gotten all of the messages required for A/C and cruise control buttons already, so not having a vehicle to test on its really just the limiting factor.

Once you get a car going, would you be able to confirm that it would work with an E40 ecu?


Could you also confirm the previous statements by @DustinS that the “A/C will need the compressor trigger wired from GM to the BRZ harness”?


Thanks & I look forward to working with you!

The first vehicle I did is an E40. I am still working on code for those ECUs. The older GM CAN stuff is rather tricky as it extends from 05-2012 in many different chassis requiring many different combinations of signals.

Once the GM A/C request is working, the vehicle will think it is commanding the A/C compressor the same way it would in a factory vehicle. Follow the factory wiring diagram for your GM PCM to control the A/C clutch.

The E40 ecu is "that" ecu. I pulled my complete setup from an 06 Envoy. Well I pulled my first setup from an 05 envoy and didn't like the direction I would've needed to take. I'd like to upgrade to a newer ecm, and i'll look more into it, but I might just work with what I got for now.