Hi Gang,

I have a 1999 motor home on an E450 frame/Triton V10 engine. After
sitting still for over a year the speedometer is going haywire. Engine
off it pegs over to the 100mph mark. Engine on, it drops back to 40mph
and fluctuates there while driving. I've replaced both the
differential sensor and the one that goes in to the transmission with
no effect.

Any other ideas before I take it to the shop?

Thank you very much in advance for any answers!!!

Regards,

DonL