Wiring up a s5 t2 ecu to my s4 Na chassis. Yes I'm going to keep the s5 t2 ecu. If a pin out for s4 Na dash harness to s5 t2 engine harness isn't possible then I need to swap chassis harness.

I only need functions for emissions, to run the engine, headlights, tail lights, signal lights. What is different between s4 and s5 chassis harnesses from wiring or experience including relays and all that jazz

 

Use the advanced search feature and use Hailers after typing in what you are searching and you''ll find posts of his which explains much what you are asking for. Also, there is no such thing as a chassis harness as they are broken down into emissions, front, engine, rear and so on.

 

Forsure. Thank you. I've changed the entire car wiring before a while back and forgot it's in a few pieces. But need everything except for emissions

 

I believe the plug sizing between the S4 and S5 are different so you won't be able to just plug in the S4 front harness which runs under the dash to the S5 ECU

 

What about swapping chassis harnesses? Putting a s5 Na chassis harness in a s4 Na. As long as I have all the s5 relays and computers it should work? I only really want necessary functions to drive the car plus the logicon.

 

Ended up swapping entire front/ engine/ dash/ rear harness to s5