When you turn your key to the "Start" position, it normally results in the operation of your car's starter and the starting of your engine. Upon releasing the key so that it goes back to the "On" position, the starter stops. Any time either of these two scenarios fails, one possible cause is the ignition switch. The Chevrolet K1500 Suburban ignition switch, which is operated by an ignition lock mechanism that is located on the top right-hand side of the steering column, is responsible for opening the circuit to the starter relay, which in turn opens the circuit to the starter solenoid, thus completing the largest current circuit that supplies power to the starter. The ignition switch's failure can cause the Chevrolet to not turn over. However, before you blame the ignition switch for your car's non-cooperation, you should check other parts of the starting system, from the battery to electrical connections and their various components. Some tests for a no-start problem are simple; others are a pain in the neck. Nonetheless, you need to find out why the car won't start.
Over time, your battery connections can become dirty or corroded; check first to make sure this isn't the issue before you turn attention to your ignition switch. A dead battery is another obvious problem; check to indirectly see if this is the case by jump-starting the car. If it starts right away, your problem is likely a dead battery.
There are lots of electrical connections in your fuel injection system. Basically, you should check all electrical connections under the hood to be sure they're tight.
If upon turning the key to the "On" position and the red warning lights on your dashboard light up, that's a good sign. If after turning the key to the start position the dash warning lights turned off, your ignition switch is A-OK. If you're still not sure, try turning on the headlights. When you try to start the car, the lights should either dim a lot or turn off completely.