Which ECU? Which car? OBD0 or OBD1? OBD0 ECU will need an RPM activated switch... The OBD1 P28 ECU will need 2 wires, one for VTEC activation, the other for the VTEC Pressure switch...
P28 pinout:
http://www.hondaswap.com/forums/inde...ype=post&id=32
Descriptions:
http://www.hondaswap.com/forums/inde...howtopic=29360