Error Code B0004

My Trailblazer gages have start going crazy off and on. it looks like my battery is overcharging at these times. It never stalls but keeps going crazy until I shut it off and restart. It used to happen every few months . Now it has been everyday for 3 days.

camshaft position code came on and replaced. No codes now but noise still there. If you touch bottom of engine you can feel vibration and metal on metal sound. Any ideas? Any recalls

I found out the hard way that my front differential is not engaging.
Any know problems/fixes?

I turn on the A/c and the blower only runs on low. I shut off and restart the car and fan runs normal in auto mode. This happens randomly. Once it works normal, I have no problems until I shut the car off again

The vibration goes away if put in neutral or park, or when the engine is warm. I have 125,000 miles on it and the transmission fluid & filter was changes at 70K and 120K. what is wrong?

back on for a few thousnad miles. Whats required to correct problem ?

Electricity proplem with left front door

replaced low pressure switch. problem still persists

found passenger seat beat not bolted. could this cause system to fail? rebolted but problem persists. dealer wants 1200 just to try a fix. no guarantee

Steering wheel also doesnt lock and replaced neutral switch

Engine shake at idle when cold in drive until reaches full operating temperature and runs smooth. It runs smoother when I shift it in reverse while idling even before it reaches full operating temperature. Engine is 4.2L L6