If you look at the Pinouts I just Posted you will see the difference in the two, Your better off buying a Conversion harness... Its Cheap and its Plug and Play.. Oh and if you are tring to plug the p28 into the 89 Harness it will not fit.. You will need to find a Obd-0 Ecu with Vtec... Explain to us what Harness you are useing for the car and for the Motor...