Riddle me this?
I have been watching/taking notes and testing this for 3 weeks now and the results are very consistent. Both alternator and battery are brand new and i had the alternator swapped because I thought they sold me a bad one, so this is the second new alternator with the same results. Note: I have an Autometer volt gauge and a Scangauge II, both read the same voltage.
When I first start my car, my alternator puts out around 13.6-14 volts, this is tested at the battery and the output of the alternator with a Fluke multimeter. The car runs fine until it warms up, thats when the trouble starts. The voltage will start to steadily decrease until the car is up to full temp (coolant temp reads 190-210 on ScangaugeII) and after about 1 hour of driving, the alternator is putting out about 11.4 volts, again tested at the batt. and the alt. output. Once everything under the hood is hot to the touch I see this condition. I can turn the car off and let it cool down and after about 30 minutes its back to 13.6-14 volts again. I never had this issue during the winter months. I have not had any issue of not being able to start the car, but I fear its around the corner.
Is the voltage regulator in the alternator controlled by the PCM? Could there be something wrong with the PCM if It does control it? Any one ever see this before? Does anyone have a schematic of the electrical system that shows the plug on the bottom of the alt. and where the wires go?
Thanks, this 100* Texas heat is killing my car.
