What is it and where is it and what does it do.. looking for reason car is not starting?

Rosebudboyer, if the CEL comes on for 2 seconds and then goes out, when the ignition switch is turned to ON (Position II), then focus on the distributor. It sounds like you installed an aftermarket distributor. Over 50% of them don't work at AMHD--the remaining ones are not reliable and are problematic. I would install a new genuine Honda distributor housing with an aftermarket igniter and coil, to keep the cost down.

It's not likely that the main relay is your problem. They become an issue when the car does not start in the heat of the day, due to the cold solder joints expanding on the PCB.