I'm not sure if my overdrive is working, whenever i change into overdrive the engine goes 1000rpms faster than before. is this normal or is there a problem with the solenoids/relays? or even the whole overdrive. Thanks.
Errrm that sounds like switching overdrive off.

Auto experts, assemble!
Engaging overdrive = dash light OFF, and revs decrease
Disengaging = dash light ON, and revs increase

(And overdrive turning on and off whenever it feels like it = my car.)