now that the weather is starting to get colder I.E. upper 40's in the morning after i fire up the truck im not charging, my volts are 10-11 let it idle for five minutes or so then i take off and within two blocks im at 14.5ish then i will stay there forever. or until the next morning, and if i take off right away it takes about one minute for a charge to start. the real problem is i cant replicate the problem at a shop cause when its warmed up it charges right away.

 

Grid heater is cycling. What it is, is a giant heating element that warms the air coming into the engine. It draws a lot of amps, and when they kick on is why your volt meter drops.

 

And further, the ECM fakes the reading on your volt meter so that the gauge doesn't jump with the grid heater cycling. It looks bad planted that low, but it should pop up to normal after 205 seconds (I think that is the right time period) or if you exceed 25mph. It also shuts off at temps over 60*F...

You should see the actual voltage when its cycling...they drop to about 12.5 and jump up to over 15Vs during catch up.

 

Thankyou thats really good to know. wish the owners manual would mention that