P0343

If the only problem is that the CEL is on and no drivabilty problems present, then I would follow a TSB that says to replace the Cam sensor with part number 12572656.

Is that a 5.3 motor?

Just for clarification, the starter cranks, but combustion doesn't happen. Or nothing happens when you turn the key.

I would treat this as a no start, but not follow the path of the Codes on this one. Checking either code starts with testing with the engine idling.

Start simple and check all the fuses and maxi fuses. There are a couple fuseboxs, and I think they are different between the new body stayle and the old.

I may be that the sensor(s) are bad, but it may not be. That's why I would treat it as a no start diagnosis first. Find out if your losing spark and fuel or if timing is a problem. The Cam sensor may very well be the problem, however I have seen other problems kick up the code like a broken valve spring. Granted there were misfire codes also in that situation.

As far as the high voltage, the sensor sends it's values of what it is measuring in volts. There may really be a reason for it reading high volts. Since you are cranking it and it isn't firing you have a reason for it to throw this code.

Spray some starting fluid or carb cleaner into the throttle bore and then crank it. What does it do?

Still didn't run for a minute off the cleaner, pull a plug and have the the plug near a grounded part and see if it sparks when cranking. Really should use a spark tester.