5.9L, 4x4, gas, auto transmission, 115,000 miles.

When I turn the ignition switch to start the engine, I get one click. When I release the ignition switch the ignition module vibrates/humms briefly. If I repeat the attempt to start the engine, I get the same result 5 or 6 times until the engine finally starts. The battery cranks very strong when it is engaged so I don't think it's battery related (the cables are tight and clean). I'm guessing it's the engine control module???? I sure hope not. Any help would be greatly appreciated. Thanks very much.