Honda OBD0 OR OBD1 trouble codes (pull without scanner).
 

Without a scanner you can get pre-OBD2 codes, and apparently even some OBD2 codes with a simple piece of wire jumping a small blue 2P connector, key in ON position, and counting the long and short flashes of the CEL on the car's instrument panel:

https://www.youtube.com/embed/8M5BaA...watch&vnddnc=1

The OBD0 isn't standardized. I know that in the 88-91 generation of Civics, you just look at the little window in the ECU and count the number of blinks of the LED in it. The Check-Engine Light (CEL) tells you that you need to look at the window.

On those cars, the only connector that you short (with a wire or a paper clip) disables the automatic adjustment of ignition timing, allowing you to set the timing.

-soD