i have a 2004 titan, when i first start the truck it will go into reverse, however if i drive it around and put it into reverse, it acts like it is in neutral. I have to turn the truck off and back on and then it will go into reverse.
when working it shifts in nice, it spins the tires in reverse
it sat for about 3 months, i hooked up a jump box to it and when i went to start it the gauges were going crazy and still wouldnt turn over, i trickle charged the battery and started, i am not sure this had anything to do with it, but it had always shifted fine up until then.