Manolis_D

iTrader: (2)

Like it says... What does the ECU do / control in a S5 NA? I have a Haltech and a S5 J-Spec motor that I'm putting in, and I need to figure out what wires I can eliminate! Can I get rid of the passenger side wiring harness? What do I do with the driver's side harness?

Or if anybody just knows what the ECU controls, that'd be great too

Thanks!,
Manolis

scathcart

You can eliminate the entire ECU and wiring with a Haltech. This includes the passenger side wiring harness. The driver's side harness must stay.
The Haltech is an aftermarket ECU, it does the job of the stock ECU.
Asking a q like that, are you sure you're ready for a complicated mod such as a Haltech install?
Sean Cathcart

Manolis_D

iTrader: (2)

As ready as i'll ever be . I thought there were several things <wipers, cruise control, AC, etc.> that were controlled ('affected'??) by the ECU and were in the main engine harness... Do you know if the driver's side wiring connects to the ECU?

I'm sure I can (and i will) figure this out, but It'd be convenient if somebody has already done so, so I don't have to 'reinvent the wheel'...

Thanks,
Manolis

NZConvertible

Like Sean said, are you sure you're up for this? Installing a Haltech isn't do difficult if you're reasonablt experienced with 12V auto electrics. It's like installing a really complicated car stereo! To find out what the stock ECU controls, study the ECU wiring diagrams for you car. You'll see everything that's wired to it.

Felix Wankel

The CPU on the drivers side runs stuff like that. The ECU is engine control.

Manolis_D

iTrader: (2)

OK, I guess i'll go and download the FSM

I was hoping to be lazy about it, but I guess not. Nothing like megabytes of download at a 26.4 kbps connection

autocrash

the FSM?

scathcart

Factory Shop Manual. Great for instructions for everything you do on your car.
Available at www.FC3s.org.
Sean Cathcart

HAILERS

If the later fsm are anything like the 87 fsm, then just download the FUEL section. In the 87 fsm there is a part of the FUEL section that is called CONTROL UNIT. It gives a list of what each pin on the ECU does. I think on that fc3s.org site, they also have a listing of the function of the pins on later model ECU, like your car. You might take a look at that site prior to downloading the fsm.

HAILERS

Here is an example out of a 87 manual. Its mostly fuel delivery, timing and emissions:

HAILERS

And two:

HAILERS

And three:

Manolis_D

iTrader: (2)

Oops, i missed you're comment Felix... Sorry for the confusion -- the metal box under the passenger kickplate is the CPU, correct? Can I remove this completely while wiring up the Haltech?

I looked at some of the factory wiring diagrams, and it looks like the headlights, etc. run through the CPU. What do I do about the lights, etc? (I know somebody has already figured this out )

Thanks,
Manolis
...as soon as i get some real time i'm going to d/l the FSM and take a look at the entire wiring diagram to figure this out....

Felix Wankel

There are two seperate boxes. ECU and CPU. The CPU is on the drivers side. Thats why they are telling you to leave the drivers side harness. Pull the passenger kickpanel and plate off of the floor, then you can yank the ECU and passenger side harness.

A Haltech doesn't take a brain surgeon to install

TonyTurboII

I was somewhat confused by this too. I can remove the ECU and all of its wiring that snakes to through the firewall? Id like to know, more **** I can sell for a haltech!

Felix Wankel

Buy the Haltech with the flying lead harness, and sell your TII ECU, harness, AFM, etc. to some sap, er, fellow rotorhead for good money.

TonyTurboII

Sweet ***. Flying lead? Screw that, ive got the "Fully terminated for the FC" hookup.

Scott 89t2

you are part correct. the wires for the wipers are wraped in the engine harness, as well as I think the oil pressure or one of those. you will need to run a few new wires after you rip out the harness.

I have some haltech install info on my site written by brain cain. click my sig pic.

TonyTurboII

Uh, so can I sell my harness and ECU?

And that writeup! God I am coditioned by pictures!

Scott 89t2

www.fc3s.org is going to have a full write up with pics soon if it's not up already...

TonyTurboII

I read it, its not that bad.

SureShot

All that is input to help with idle speed..

Manolis_D

iTrader: (2)

Holy crap I'm retarded -- I just realized (thanks Felix) that there are 2 computers... ECU + CPU... No wonder nothing was making sense . Hehe...

Anyway, hopefully i'll be able to start tearing stuff out and rewiring this evening!

Thanks!!!,
Manolis

PS Thanks for the link to the writeup Scott!