lights go out

[force]

just put a new alternator in our bighorn 3.2td , start it up all the lights are working , if you go above 1500 rpm the lights go out, drop back to 1500rpms and they all come back on, has anyone got any ideas? its got me stumped, could it be a relay or something else?

[geeves]

By all the lights do you mean dash lights or headlights?
If the dash lights went out at 1500 and stayed out I would of said relay as Ive had a couple of relays do that but as they come back on it has to be a lack of output from the alternator. Check the belt is tight then talk to whoever supplied the alternator as its a dud

[dasnoboarder]

Same symptoms as freshly dunked alternator (mud or water), not enough output.