need wiring help!!!!!!!!!!!!!!!!!

hey guys im new to the 240 with sr20 scene, this is where im at ive swapped a sr20 s13 into my 89 240sx wired up the six wires for under the dash on passenger side the engine cranks but no spark and fuel pump wudnt go on, so i just hooked the pump up to a manual switch, another problem is i dont think im getting power to my ecu, ive read over the swap threads and forums gone over and over it, theres one thing about the swap diagrams i dont get it says to wire in the wires behind the battery in the engine bay, ive iscolated the wires it mentioned from the sr harness but where do they go into?? im lost here please help!!!

hey i figured out my problem now my tach doesnt work its an 89 i do believe was a sohc didnt have stock motor in it when purchased, ive heard i can use a dohc cluster but not sure on that, anyone can help plz reply, thanx in advance

Pickup a DOHC cluster (or just the tach) and swap it out for yours.

SOHC is cable driven
DOHC is electronic

Another option might be to get an RB20 speed sensor as its also cable driven… but I’m unsure if it fits into the SR tranny.