I have a ZF-4HP22 auto box installed in my D90. The auto box seems to be having a problem with reverse. It goes into reverse fine and will back up on flat surfaces, but under load (backing up steep hills or caught in rocks) the engine seems to rev higher than it should and feels sluggish (no real power at the wheels). If I brake and rev the engine in reverse it will easily hit 3000-3500 RPM while in forward gears the engine bogs around 1800-2000 RPM. Does this mean the reverse clutch pack is slipping? Is there any adjustments that can be tried or does it mean the auto box it toast and needs replacement. All forward gears appear to work fine. This autobox is only 8 months old and has about 1500 miles on it. The fluid is a little dark but still has a red tint to it and does not smell burnt. Opinions? Anything I should try before tearing it out. Thanks. :(

Fluid level OK? Should be checked while cold.

Yep, Fluid level checks out. Engine cold, run through all gear positions including reverse then put it in neutral on flat surface and check level. Fluid level is right on upper line.

I think losing/slipping reverse is a tell tale sign of the tranny going out. Just had this happen in my Allroad.

Tis