About a year ago I bought a 06 Dodge ram 2500 mega cab 5,9l 4x4 with the 48re ive never owned a diesel befor let alone an auto Tran only manual so I smoked the trans quick 2 month after I got it not knowing what the heck i was doing decided to tip it out and rebuild it and after 2 1/2 rebuild kits not sure how many gallons of trans fluid, almost a devorce and 7 months later I finally got it rite but for the last 3mo this ive been fighting a P0689 couldn’t get it to clear it was Stuck in second gear it Fuentes shifted manually but would not up shift so I read and read every where and couldn’t find out how to clear it let a lone get it to even go away I was mad to the point. I put it up to sell for 2k well in the mean time I kept reading on it well ive always seen half you checked your battery’s well everyone knows there 2 battery’s always some one saying check the voltage on the all the trans sencers so this was my last option on the truck so on the drives side I took the positive off it was sluggish but it started so I did the same to the passenger side hooked up the drivers side didn’t do anything the battery’s had been in it since I bought it so can’t tell you how old they are well I replaced both battery’s it cranked over so fast idled so sweet so I took it for a drive around the block and **** if the dame thing shifted like a dream shifted in to every gear so smooth reverse included so if anyone ask you have you checked your battery’s check them becuz my code is gone haven’t came back it shifts perfect
so my advice is to change your battery’s but I don’t no anything but what I learnt but what I learnt on this escaped with my trans it’s worded for me for me P0689 is gone good luck and I hope this works for you
my apologies for the long story