just had the underdrive crank pulley taken off of the truck (2002). The next morning when I crank my truck up, everything is normal, then the dash lights and headlights start flickering, the voltage guage is moving up and down also with all of this but nothing is undercharging. I drive to work and when the truck warms up the flickering stops and everything is normal. The next morning the same exact thing happens, so I take it to the chevrolet place, but by the time I get there it has stopped. They check the battery and alternator with the machine and everything checks out, alternator is putting out 14.7 volts. So the next morning before I crank the truck up I hook a voltmeter to the battery and it reads 12.5 volts, truck cranks fine and same thing happens again. SO I go to the parts place and get a new alternator, put it on and in the morning guess what? it does it again, just till it warms up everytime. I get home in the afternoon and check every ground and cable and nothing is out of place or dirty (took it all apart and checked) All of this happens when the truck has set for probably 8 hours or so. It has been in the 30's to 50's temp wise. ALso got a new belt that doesnt help either. Does anyone know what the problem could be, I am stumped

 

So, in the morning after sitting all night it does it right after start up for a few minutes... But, after it warms up its fine?

 

yeah, right after I start it up, then too when driving up the road. It just seems to go away once the truck is driven 5-6 miles, or just enough for it to warm up. I have checked everything That you would normally check and everything seems fine. It doesnt stumble or almost shut off it is just like I have a big amp thumping and drawing current. Its irritating.

Oh yeah, my truck is a 2002, It doesnt have an air pump (smogpump), so they cant blame it on that.