My speedo is not working right. Shows 55 and hangs around there even though I'm doing anywhere from 2200-3100 rpm.

Than it will jump to 75mph.

So..........At what RPM am I doing say; 45, 55, 65, 75.

Thanks

1989 740GL Wagon Auto non-turbo

 

Same thing on my '92 740.Could be the sending unit at the differential, wiring, or the instrument itself. I took a chance and ordered a salvaged one from Everdrive. I think that's right, but will look it up to be sure. They sent me a complete instrument panel with a 3 year warranty! That did the trick.