2004 Chevy Silverado HD 2500

On many engines with distributor less ignition systems and sequential fuel injection, a camshaft position sensor is used to keep the engine's control module informed about the relative position of the crankshaft. By monitoring cam position (which allows the control module to determine when the intake and exhaust valves are opening and closing), the control module can use the cam position sensor's input along with that from the crankshaft position sensor to determine which cylinder in the engine's firing sequence is approaching top dead center. This information is then used by the engine control module to synchronize the pulsing of sequential fuel injectors so they match the firing order of the engine. On some applications, input from the camshaft position sensor is also required for ignition timing.
The camshaft position sensor may be magnetic or Hall effect, and mounted on the timing cover over the camshaft gear, on the end of the cylinder head in an overhead cam application, or in a special housing that replaces the distributor (in the case of some of the GM applications). Operation and diagnosis is essentially the same as that for a crankshaft position sensor.  

Re  check the wire harness and the sensor installation to the camshaft sensor in Bank #1 which is where the #1 cylinder is. Good luck and hope this adds some light to you question, keep me posted and be glad to help.