I have a 20 year old Bryant plus 90 furnace it does not have a dummy light that gives codes. Here is what happens Thermostat calls for heat.  Draft inducer motor starts. Pressure switch closes. Draft inducer runs for any where from a couple seconds to the pilot lighting then there is a click in the gas valve. Once that happens the inducer motor runs for ten seconds and the furnace shuts down and goes into a lock out  until I turn the  power switch back off and on again. If the burners light then it will runs it's cycle until the thermostat is satisfied. The pressure switch works the limit switch is fine the pilot and flame sensor are OK. I replaced the inducer control board last winter. So I think the problem is in the main control board the ignition lockout or the gas valve any help would be appreciated