Readers digest version! Replaced lower dash in my 02. Batteries were disconnected for a month. Big connector and the smaller connector under the dash were disconnected too. I disconnected the air bag module for a little bit. Put it all back together and now no start, odometer flashes and says no bus. No tach, or fuel gauge. Motor turns over fast. I checked all the fuses, pulled ECM connectors, cleaned them and put di-electric grease on them, checked all grounds, installed more grounds to chassis, frame and engine. Took connectors apart under dash and cleaned them. Hooked up superchips programmer will not read codes can not connect to computer. Codes on odometer are 920,921,950 and 999?