DIY: S14->S13 Harness Conversion (KA24DE)

Nov 26

Hia people…

For this project, you will need:

  • Unused s14 ecu (to cut out the connector from it)
  • s13 harness plug with wires
  • non-working power supply. * I prefer reusing/recycling so power supply seemed like a good source for “free” 18 AWG wire.  When taking the wire, make sure to test continuity with voltmeter to ensure your wires will conduct current / signal.  Or you can buy a spool of 18 AWG wire at almost any hardware or automotive store.
  • Pin out wiring (coming soon)
  • Soldering / wire stripping tools
  • Patience & Common sense: anything you see on this site you take full responsibility for.  As stated in disclaimer, I am not responsible for anything that happens to you, your car, your cat, etc.

This is based on several sources and yet to be retested (more information including detailed finalized pin out to come soon once it’s all tested w/conzult)..  I’d like to give credits for most of the research legwork to people on (JM Halder) and emance site for the pinouts they posted on their respective sites – Thanks!  I’ve combined both sheets to minimize number of pins and yet keep the consult port.

1. Cut out the connector & clip off the pins.  Avoid yanking on the bottom of the ecu board as it may break part of the plastic connector (which is where I screwed up – should be no problem as it’s just small part of it and won’t affect the function).

Trim the wires on the s13 connector (picture: left) to about 2.5″ from the connector.  For wires you won’t use – you can either tie them off or gently pop off plastic tabs on the connector & remove any unused wires (mine are removed & bagged).  Remove any spare pins from the s14 connector (picture: right) by pulling them from the front of the connector – bag these as they may come in handy and if you screw up or decide to add more ecu functions while testing.

2. If you are using new wire skip this step…

Cut your wire (read the fineprint on the wire insulator – it should say 18 AWG or 20 AWG – I like to keep all of them consistent so kept to 18 AWG).  Again test whole wire before cutting into equal length pieces.

3. Test wire for continuity before cutting.  Then cut into 5″ pieces (remember that you also have 2.5″ on the s13 harness connector so together 7.5″ should be plenty to cross-wire the far away pins like consult)

4. Organize wires into colors for each section of the harness connector (optional).  Makes it look neater and also helps you quickly verify how many pins are in each section.  Also helps with wire tracing.

5. Now with pins eliminated, you got more space to solder…

6. Done…

7. Print out the pin-out list (coming soon).   It is sorted according to the s13 pin out and you can check off on the list each pin and mark on the diagram to verify that you’re doing it correctly.

8. Ok all wires are done – time to verify your work.  Check your pins again – make sure they are not sticking together or they could cause a short.  You can also set the connector on it’s side and take 5-10 mins to check with voltmeter that you are getting continuity from the s13 pins to the correct s14 pins.

9. I prefer to test anything electrical before I seal it up – so before epoxying.. Depends how confident you are in your work, you could seal it up.  In my case, I’ve done some wiring changes from the original pinouts I’ve seen so it needs testing.  If you decide to do this, make sure that none of the exposed wires are contacting each other or you may fry something!  During testing I usually run thick strip of rubber covering the rows of connectors and spread them out horizontally to ensure no contact.


  • new pin outs (excel)

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