RD28t auto transmission problem

[Dazdeb]

Hi All,
Just trying to get to the bottom of a fault with my auto gearbox so I thought i would consult the experts :bigthumbup:
While in overdrive truck stays in gear nicely up untill 4th, when it changes into 4th it stays there for about 2 seconds then overdrive drops in, I cant seem to get any acceleration in forth when OD drops in, once OD drops in the trucks starts to loose speed.
Any suggestions would be greatly receieved.
Cheers from NZ

[mudnut]

When is the last time the box was serviced? Have you checked the fluid level and condition? Is it clear, murky or dark? Does it smell burnt and leave black deposits on the cloth you wipe the dipstick with?

[Dazdeb]

Thanks Mudnut for the reply, I changed the oil last week along with T-case and diffs.

[mudnut]

Ok. Was the fault there before or after changing the fluid? What condition was the filter and fluid? Did you knock or play with any of the wiring connectors or wiring harness?

[Dazdeb]

Problem was there before thats why I changed fluids. Fluids are all new, filter clean, and all wires checked including plugs. No much more to check, its got me stumped as to what it is.

[NissanGQ4.2]

What are the driving conditions? Flat road highway high speed, up hills slow speed etc?

Do you know what auto gear box is in it?