RB20DET Wiring Guide For Dummies

Applied Vehicles: Vehicles with RB20DET swaps Difficulty Rating: Estimated Labor Time: Not Applicable Written By: HIGHFIV5 Estimated Total Cost: Not Applicable Find related tutorials and information on your vehicle in NICOclub’s RB20DET / RB25DET / RB26DETT Forum

During my swap i decided to make a wiring guide that even the biggest noobs shouldnt have a hard time following. I looked at all the various guides out there and added what they were missing and clarified the bits that may confuse others. During my wiring i traced every wire back to the ECU pinout and verified its location and use. The result…started up first try without any troubles! I hope this guide can help anyone figure out the wiring for their S13 and save them a couple hundred bucks so they can dump that into their car or motor. The wiring isnt something anyone should be afraid of…I’m 18, this is my first swap and my first attempt at the wiring and i had no problems. I reccommend starting with the cleanest most unmolested harness you can. This will make things a million times easier. Also, dont use butt connectors….i used metal crimps that you also solder afterwards for all my connections. And shrink wrap people not  electrical tape. Finish it all off with some fresh loom and your good to go!


Anyways onto the guide!
*Note that this is SOHC—RB20 so their might be some difference in DOHC but this should set yeh on the right path regardless. Also, with it being SOHC, my tach did not work…need a DOHC, or tach config, or aftermarket or R32 tach.

I will include pics of the plugs and such so again there is no confusion as to what plug is being mentioned.

These are all the wires functions in the various plugs.

S13 BROWN PLUG

SOLID/STRIPE

BLACK/PINK————- FUEL PUMP
GREEN/ORANGE——- NEUTRAL SWITCH
BLACK/YELLOW——- IACV POWER
RED/ BLACK————- ECU RELAY
BROWN——————- 02 SENSOR
BROWN——————- 02 SENSOR
PINK———————– N/A
YELLOW/GREEN—— N/A

S13 GREY OVAL PLUG

BLACK/RED(THICK)———– MAIN IGNITION POWER
RED (MEDIUM)—————— ECU BACKUP/CONSTANT POWER
BLACK/WHITE(MEDIUM)—- ECU POWER
BLUE/GREEN——————– AC RELAY
GREEN/YELLOW————— AC RELAY
BLACK—————————- GROUND
RED/BLUE———————– N/A

These are the brown and grey S13 plugs you need to use. They plug into the main fuse box on
the passenger side. Note the tape…i recommend marking all the wires that you will be using before doing
any wiring. Makes things very easy to navigate and the whole wiring process quicker in the end.

S13 DASH PLUG

YELLOW/RED——————- TACH SIGNAL
YELLOW/GREEN————— SPEED SIGNAL
ORANGE————————– IGNITION START
BLUE/BLACK——————– WATER TEMP SENSOR
BLUE/GREEN——————– AC SIGNAL
RED——————————— CHECK ENGINE LIGHT
BLACK—————————- GROUND

This one shouldnt be hard to find at all…but here’s a pic anyways.

RB20 SQUARE 6 WIRE PLUG

WHITE PURPLE(THICK)———– IGNITION RELAY
RED/BLACK (THICK)————– MAIN IGNITION POWER
WHITE/BLACK (MEDUIM)——- ECU MEMORY
GREEN/ORANGE——————- NEUTRAL SWITCH
TEAL———————————– N/A
LIGHT BLUE————————- N/A

This is the RB20 6-Wire plug. Its a big ugly grey rectangular plug.

RB20 DASH PLUG

BLACK/PINK——————– FUEL PUMP
YELLOW/RED—————— TACH SIGNAL
YELLOW/GREEN————– VEHICLE SPEED SENSOR
BLACK/YELLOW————– IGNITION START SIGNAL
ORANGE/BLACK————– CHECK ENGINE LIGHT
TEAL—————————– AC RELAY
TEAL/RED———————- AC SWITCH
*NOTE*—— FSM states PIN #32/Check engine light as PINK/BLACK
But mine was ORANGE/BLACK

I’m going to include the wire-wire as well as the plug-plug locations to sort out any confusion that could be had during the wiring process.

S13 WIRE/RB20 WIRE
SOLID/STRIPE

DASH PLUG WIRING

YELLOW/RED——————- TACH SIGNAL—————— YELLOW/RED
YELLOW/GREEN————— SPEED SIGNAL—————– YELLOW/GREEN
ORANGE————————– IGNITION START————– BLACK/YELLOW
*NOTE* The BLACK/YELLOW wire should trace back to PIN #43, which you might have read about on the other guides.
BLACK/PINK———————FUEL PUMP———————- BLACK/PINK
S13 wire found on the BROWN plug. RB20 wire found on the DASH PLUG.
I actually extended the wire from the dash plug to the brown to make sure it would reach
and plug in.
RED—————————— CHECK ENGINE LIGHT————– ORANGE/BLACK
BLACK—————————- GROUND

Fuel pump wire on the RB dash plug.

RB20 SQUARE 6 WIRE PLUG—GREY & BROWN S13 PLUGS

S13 WIRE/ RB20 WIRE

GREEN/ORANGE——- —–NEUTRAL SWITCH————– GREEN/ORANGE
[BROWN PLUG]
RED (MEDIUM)———- ECU BACKUP/CONSTANT POWER——WHITE/BLACK
[GREY OVAL PLUG]
BLACK/RED(THICK)——– MAIN IGNITION POWER——BLACK/RED(THICK)
[GREY OVAL PLUG]
WHITE(THICK)——– —–IGNITION RELAY———— WHITE/PURPLE (THICK)

[LOCATED IN FUSE BOX. WILL LIKELY HAVE TO PEEL BACK THE LOOM. THERE WILL BE 2 WHITE WIRES. ONES REALLY THICK AND THE OTHERS NORMAL THICK. YOU OBVIOUSLY WANT THE NORMAL THICK ONE.

This is the last wire you should worry about. Dont wire this one till the harness is all routed through the
firewall and such.]

Here’s the ignition switch wire in the fuse box wiring. You gotta cut it and strip both sides.

I tied the WHITE/PURPLE RB wire into the one side of the WHITE S13 wire then crimped them together then crimped the other half of the WHITE wire into them then soldered and shrink wrapped.

NOTE: Be sure to extend the MAF and O2 sensor plugs before doing this last step as it will be much easier outside the car. O2 needs approximately 3 feet and MAF needs about another 4 feet. Be sure to use shielded wire.

Here is the finished product! That wasn’t so bad now was it?

As far as the lower harness goes….just use the KA lower harness. Pretty much everything plugs in with the exception of the oil pressure sensor in which case you can splice the RB plug on or just use the KA oil pressure sensor or go aftermarket. Also, i stripped AC from my car so did not include AC wiring in this guide but did include the wires that are for AC.

Last but not least. I found these two resources to be some of the most useful. I verified every wire back to the ECU and recommend you do the same. Not every harness is the same so check to be sure. These lase two pics though i cannot take credit for. The first was made by a fellow NICO member and was found on one of the threads here. I verified every wire with the FSM.

And use this to find the pin location.

Hope this guide serves as a valuable resource to everyone and helps you get on the road with your RB20!