Method 1: switch off of the engine and short the two pin connector with the jumper wire, start the engine and note the "check engine" light on the gauge cluster it will blink in a particular pattern indicating the service code. It is all explained in its manual....
Method 2: Scanner tool can be connected with the 3 pin connector. But unfortunately there are no scanner tools available for OBDI type interface. However, there are adapter cables available which convert the Honda 3 pin OBD1 connector to 16 pin OBDII connector, the latter can be attached with OBDII type scanner tool for acquiring the error code.