Now to clear things up, many people emailed me saying to use the Accord harness and just add the VTEC pressure, VTEC solenoid, Knock Sensor, and Intake Air Bypass wires and you are set. Similar to a B series EG swap, easy right? Well, the truth is actually much, much darker...
First of all, about half of the wires for the sensors have to be relocated/lengthened. This is difficult going into the whole thing blind, and you will spend a significant amount of time cross referencing wiring diagrams in you Helms. I will spare you that pain. Also avoid "mickey-mousing" it, buy some flex tube and tape so you can give the illusion that the wiring was not done by a drunken blind man.
Also, and I can't stress this enough, CHECK YOUR GROUNDS. They are the cause and solution to all of lifes problems!
*Wires to add:
VTEC Solenoid: Grn/Yel on Prelude harness > Pin A4 on ECU // SENSOR LOCATION: Near distributor
VTEC Pressure Switch: Lt Blu on Prelude harness > Pin D6 on ECU // SENSOR LOCATION: Near distributor
Blk/Red > Ground
IAB: Pink on Prelude harness > Pin A17 on ECU // SENSOR LOCATION: Drivers side of intake manifold
Blk/Yel > 12V
Knock Sensor: Red/Blu on Prelude harness > Pin D3 on ECU // SENSOR LOCATION: Middle back of block
*Sensors to lengthen:
(NOTE: Consult the helms for the location of sensors, and color code of the wires on your harness.) Colors below are for the Accord LX harness.
IAT (GRN/BLU-RED/YEL): Too short, needs to reach drivers side of intake manifold.
MAP (YEL/WHT-GRN/WHT-WHT/YEL): Too short, needs to reach wherever on the firewall you mount the MAP sensor.
EGR Lift solenoid (GRN/BLU-WHT/BLK-YEL/BLU): Too short, needs to reach passengers side of intake manifold.
H02s (GRN/BLU-WHT/RED-ORN/BLK-YEL/BLK): Too short, needs to be run to O2 sensor, near oil filter.
IAC valve (BLK/BLU-YEL/BLK): Too short, needs to reach top of intake runners, in the middle.
ECT switch A: This will need to be extended to the thermostat housing on the passengers side of the back of the head. The ECT sensor and ECT sending unit fit fine (under the distributor.)
*NOTE: There is no ECT switch B on the JDM H22, just spare back the connector.
Alternator: The power wire on the alternator needs to be lengthened about 2". We just cut the one off the Prelude harness, and attached it to the Accord harness with a large enough splice.
*NOTE: SWITCH WIRES A6 (EGR solenoid) and A11 (H02S heater) at the ECU
When you think you have everything wired up correctly, plug in the brick and turn the key. Have a multimeter ready to troublshoot if you throw codes. Remember, some of the sensors may be bad so don't run yourself into a wall thinking you wired wrong. (Although you may have.)
The VTEC stuff won't have to be wired if he's got an EX. And as for all that other stuff....I know it's been a long time since I did my swap, but I don't remember all that work. I wired up a knock sensor, switched pins A6 and A11 at the ECU, and I think that was it as far as wiring went. My friend helped with the wiring, but I don't think his wiring job was nearly that extensive...