1990 735i

Not sure about the box in this model, but if it's old enough to have an engine vacuum controlled box, the pipe has come off or the modulator valve failed. But it should still change up at near maximum revs.

you may also want to make sure that your transmission service bulb has not burnt out, it sounds like you are stuck in limp mode due to a failure of some sort.

Thanks ! The trans is electricly controlled and the light comes on to indicate gear shift position etc.

I'd check the connector to the gearbox is clean inside.

It sounds like there is a fault being read in your transmission computer. Could be something miniscule or something huge. However, I've seen that happen before. Try a battery disconnect for a few hours to reset, if its still a problem your going to have to take it in as it is in "limp mode", designed to allow you to still move, but hopefully to prevent you from doing any more damage to the problem component.

Trans is fixed!!! Kickdown switch stuck.