When it rains I get po641 code. Truck goes to reduced power. Only when it rains. Last week the truck set for 4 days while in florida the code was there when the truck was first started. I unhooked both batteries turned the head lights on for 20 min. After that the truck was fine for 2 days of driving in dry conditions. Yesterday drove into some rain it started to throw the code at 70mph pulling 20ft trailer. I could reset it quickly with my code reader. It would be ok for 5 miles and do it again about 20 times. Finally drove out of the rain and it rain perfectly for 800 miles. This has happened in the past a few times. Again only in the rain. I plow snow with it. Never had the problem. I have checked wires recovered them. Any ideas other then a deep reservoir. Next on my list
