Not charging issues
 

I presume that this is a continuation of a previous thread.

Did you check all the cable connections as previously advised? Did you find any with corrosion? If so, how did you clean them?

Disconnect the ground from each battery and then using a multimeter (NOT the truck volmeter!) check the voltage of each battery and tell us what that voltage is.

Now reconnect all the cables and start the truck. Before starting the truck, make sure that the crossover cable has clean connections and is properly connected. Using the multimeter and with the truck idling, again check the voltage on the battery posts (not the cable terminals) and let us know what the voltage is on each battery and note which is left and right.

When you started the truck, what was the approximate outside air temperature? Did the wait to start light come on before you started it?

That click that you heard may have been the grid heaters coming on and if so, they will bring the voltage down big time and is not a problem. It is normal. Now wait for the engine to warm up or take it for a spin around the block. See if the volt meter in the truck goes up to a normal charge while you are driving over 20 mph. Once the truck has warmed up and the voltmeter in the instrument panel goes up, again using the multimeter and with the engine idling, check the voltage on each battery post and tell us what the voltages are on each battery.

Do not be surprised if a code has been set by you starting the truck on only one battery. This code may go away in time or you can get it cancelled.

Sounds like the grid heaters activating as Mexstan mentioned and if so normal. The max cycle time (depending on temp) for the grid heaters on an 01 is 180 seconds (no idea what year your truck is though)