This is what happend I was driving on a jeep trail after rain and snow. I came up to a mud/water crossing it was about 50' across. I had crossed many that day none realy needed 4wd. So i got a little momentum and attempted to drive thrue turned out that it was about 3' plus deep with deep ruts and holes under the water where others had probably been stuck. Got right out to the deepest part tracked into a rut sank into a hole and bogged down. Kept it running. I put it in neutral and shifted into 4 low plowed forward to make a little room to rock it back and forth till I started to make some ground mabe 10'. continually shifting from drive to reverse over the 10' to get up and out took many attempts and over 20 minutes. The floor boards filled up with 4" of water. Now the problem is once I got out and shifted into 2wd my xj was lacking power but I figured some water/mud may have been obstructing some of my exhoust flow. Figured I'd head towards home while it was still running about 2 hours from where I was stuck. The xj would not "kick down" when accelerating hard (figured I'd try and blow out some water from the tailpipe) By the time I got home the battery gauge said 9v and when i got to my house it couldent Drive up my driveway a 10º slope the motor spins up and it bearly moves at all. I put it in 4wd and the front pulls up fine. So the water in the floor boards probably got into a wire loom and drained the battery. As for the rear diff the only thing I can figure is a broken drive shaft because it moves a little and drove all the way home in 2wd. It's not making any unusual noises and I never heard any grinding or pops. Kinda feels like the parking break is on but the cable is clearly not engaged. Maybe locked drums? Ran great its all stock aside from push fans, hood vents, headlights and k suspension injectors. Lack of power and no kick down mabe clogged muffler or cats? Mud in air box but filter is clean. Water in diff? water in gas tank. Water was up to the driver door handle and serged over the motor... Any info would help. I've never swamped a vehicle... I'm going to put it on stands and check rear diff is rotating? Then open rear dif? Try to check for water in exhoust and anywhere else. Thank you for your time.

 

my first bet is your auto has ingested water because the breather hose is missing ?

have you checked the auto trans fluid ?

a voltage reading of 9V could cause many issues, the PCM wont like that