When I start the car it shows between 11.7 and 12 volts from the charging system. Once it warms up ( I let it idle for about 10 minutes) suddenly starts charging 13.6 to 14.1 volts. Once it's warm can turn off the car and restart no charging problem, but if you let it cool down goes through the same warm up thing and then starts charging again. I tested the ipdm with the on board test and everything seems fine. Could this be the pcm?