Voltage issue 2004 5.7 Hemi

[chris.dusek.12]

I am running into a voltage issue. I recently replaced the altenator and the PCM and it has a new battery. However, when it's cold I've noticed the voltage does not immediately come up when I start the truck. It also tends to idle rough and the rpm's surge at idle. Not sure where to go next. Any suggestions? All connections look good and I'm not getting any check engine codes.

 

[NYCruiser]

Not sure, but the idle issue could cause it being slow to reach charging threshold. I'd pursue the idle when cold problem and see if it straightens out the charging.

 

[chris.dusek.12]

It appears to me the idle issue may be a result of the voltage issues. Just seems strange all of this started when the temperature dropped. It doesn't seem to be a problem when it is warm outside.

 

[NYCruiser]

I don't think not charging right away would affect the idle. The truck should run fine without an alternator if the battery is charged up. You're thinking its getting low spark voltage? I think it would either run or not. More likely fuel or intake related at cold temps. The unsteady idle gives unsteady output from the alternator.