My civic 92 cannot start the engine.. since I turn ON the switch there is no sound of relay click.. I already change the main relay,brand new item.the problem is still the same and the check engine light is still goes on.all the fuses under dash,under hood is OK.the fuel pump also OK.. distributor also OK.

The ECM is likely bad. Perform the K-Test on the ECM:

The K-Test: Remove the MAP Sensor connector and turn the ignition switch to ON (Position II). Using a multimeter, check for 5 volts going between the MAP Sensor connector's reference wire (+) and ground. As you look at the connector, this is the socket on the right. Really press the black test lead into a cleaned main ECM ground on the thermostat housing. If the voltage is low, it’s probably indicating ECM failure. Most failed ECMs will record a fraction of a volt. To me, the K-Test is simple, elegant, and accurate.