Well finding this thread ,now I know I am not crazy.
Bought the truck about 6 weeks ago and the first few times I connected via Bluetooth with my iphone, I found my volume down.
Thought I accidently turned the volume down myself at first but started thinking it might be an issue with the radio.
Didn't really had time to look into it and in the mean time
I updated the iphone trough the new software notice on my phone and I noticed that I don't have that issue anymore.Well for now the issue seems to be resolved.
I personally linked the correction of the issue to the phone's software update. Maybe I am wrong but I think it's worth the try .