Full write up for RB20DET swap into 1990 240sx S13 SOHC(Sorry for the poor pictures)SOLID / STRIPEBLUE / BLACKDash plugsRB20DET 240sx S131. Blue / black -----------Water Temperature----------- Blue / black2. Yellow / green --------Speed Sensor------------------ Yellow / Green3. Black ------------------ Ground ------------------------- Black4. Yellow / Blue -------- Tachometer -------------------- Yellow / Red5. Blue / Green --------- A/C ----------------------------- Blue / Green6. Black / yellow ------- Start Signal -------------------- Orange7. Red / White ---------- Check Engine ------------------ RedDuring the wiring on number six you will need to connect the 240sx orange to pin number 43 on the Rb20 witch is the Start Signal.

Engine plugsRB20DET 240sx S131. Black / Red ----------------------------------------------- Black / Red2. White / Red ------------Constant Power -------------- RED3. Black / Pink ----------- Fuel pump --------------------- Black / Pink4. Green / Orange ------- Neutral ------------------------- Green / Orange5. Green / Yellow ------- A/C ----------------------------- Green / Yellow6. White / Purple -------- Green Relays ------------------ WhiteDuring the wiring on number three you will need to extend the black/pink from the brown plug off the 240 and run it into the passenger floor board and connect it to pin number 18 on the RB20DET ECU witch is the fuel pump signal. Now on Numbers one four and six are on the Six wire grey plug coming off the RB20 harness. Number one is on the Grey oval plug on the 240 and connects to the six wire plug on the RB20 harness. Now the white/purple you must connect to the white wire going into the fuse box from the chassis harness. I connected mine to the ignition switch fuse witch is the white wire. The Green/orange is on both the 6 and 8 wire plugs on the RB20 harness. I just took and ran a wire from one to the other and then ran it to the 240 green/orange. Now on the 8 wire plug that looks just like the six wire plug you will be dealing with the white/red witch will connect to the solid RED. I am not runnig A/C but if you choose to just run the A/C wire all the way back close to the ECU and that should do it.

Transmission HarnessThere are a couple of ways to do this. You could take and switch all the sensors off the KA transmission and put it on the RB transmission. Then youll have to switch out the plugs on do more wiring. That’s more work. The way I did it was just used the Rb20 harness. There was a black thick wire hanging out of one side so I grounded that. Then there were two little plugs, one with a black/yellow and a solid black and the other with a black/white and a solid black. I grounded both black and took the black/yellow and black/white and ran them as a power.

O2 and MAF sensorsAll you have to do is extend these so they reach to their points. I extended mine to where I can do a wire tuck in the future. Its all up to what you want it to look like but you do have to extend them.

. The starter wire id black with a yellow strip connected to starter is that hooked up???? Check starter 12volt cable is hooked to upper center terminal and you have at least 3 ground 1 battery to motor and 2 motor to body…this might help with any starting problems.if this does not help... adjust the switch that gets pressed in when you press in your clutch. this might also help

Documented by JUSTIN BATSONModified by RB20DET_240SX at 10:55 AM 5/24/2009

Modified by RB20DET_240SX at 11:59 AM 5/29/2009

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Modified by RB20DET_240SX at 10:44 PM 6/12/2009
Modified by RB20DET_240SX at 10:46 PM 6/12/2009

I haven't had to extend my o2 or maf wires yet. All I did was unwrap the harness going to that side of the car.

And for the black/pink fuel pump wire, I stripped the same wire off the SOHC ecu harness, so that way the colors match and its a lot easier to trouble shoot later on.

~Alex

good info. first time ive seen someone address the lower harness and the ignition/eccs relays like this. Add to sticky!

After my car runs I'm going to do an idiots guide KA24E to RB20DET guide. Which that's this weekend

~Alex

thank you cant wait to try this out. your pics arent working and RustspecS13 i cant wait to see your write up so that we compair them and make sure both are correct

damn good write up!

currently using this for my swap. i had to cut the white plug though and just hard wire the RB harness right in which included me pulling the dash, because i had a DOHC KA harness and my car was SOHC but whatever, it will work and someday i will re-wire and take out all the unnecessary s*** thats in there anyway. but good write up! i'll let u all know how it works out when the swap is done.

while we're at it what about the reverse wire?

i didnt have to do a reverse wire... ill check into it and post it in with the write up. just keep checking back on it

Hey batson, i am now the previous owner of your old 240sx. I have really been trying to get ahold of you man. I have a question about the car. Car started and ran fine for a good while but every once in a while it would die. Well now the car doesn't want to fire at all. It will just sit and turn over, I checked for fuel and spark, yes. Coilpacks tested good, and then I got to the power transistor unit (igniter). It was laying off the back of the motor and I noticed it should probably be bolted on somewhere??? So it will ground out?? It seems to be not getting ground, give me a holler at my email please! [email protected]