My dad bought this truck new in 07. From the time he bought it, he has had battery issues. They just randomly go dead. Sometimes it will go 6 to 8 months and be perfectly fine then usually when winter comes around they will start acting up again. for instance he got up this morning and drove to work. The batteries are perfectly fine. Attempts to go home and they are both dead as a door nail. Initally GM thought they found the problem by disconnecting the windshield washer fluid heater. They found the harness melted and said there was a short in it. He told them he wasn't worried about it and they just disconnected it and pulled the fuse. Well now the problem is back. I have some questions about how the two batteries are connected together. I just assumed they were hooked in parallel with a direct connection. Here is the thing that is confusing me. With the truck off, when the batteries are weak or dead, you read two different voltages on the batteries. One is reading 12.3V and the other is 11.2V. This is impossible if they are tied directly together. Now i think the positive side is tied together through a cable and im not aware of any relay or anything. If this is the case, then to me it has to be a break in the ground connections and they are no longer sharing a common ground. Has anyone out there had any issues like this with this type of truck? also these are stock Delco batteries if it makes any difference.
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