Using a 97 "EX" engine wiring harness.. how would you wire for the Secondary 02 sensor? The Primary 02 sensor plugs in... but there is no plug for the Seconday 02 sensor. The "EX" chassis has the secondary 02 sensor plug at the dash that runs who knows where.. I read the Honda book and wired 3 of the 4 wires directly to the ECU.. but the 4th wire (Black) that is supposed to go to charcoal canister / junction block.. I tapped in to it under the hood and I still get a low voltage CEL. I put the "EX" engine, "EX" engine wiring harness, and "EX" computer in my "HX" chassis. Any thoughts appreciated..