I have a 1999 U320.
With out head lights on, all the gages that use electricity (fuel, temp, oil pressure, etc) work fine.
With head lights and dash instrument light on. All electrical gages increase in value. Example, fuel guage increases a 1/4 tank, instead of half full, it shows 3/4 full.
With headlights on and dash lights off, gages work as advertised.
Anyone got any idea.
Re ground all of the wires at the ground post under the dash and at the corners of the coach , to the frame.
John,
I'm pretty sure that Mike's recommendations will solve the problem. On the other hand, leave it as is and if you ever run critically low on diesel, just turn on the lights.
Owning a motorhome you have to keep a sense of humor.
Richard
Yup, poor ground from dash instruments is the most likely suspect.
mine had the same problem --I pit in a VMSPC (silver leaf) system and rarely look at the dash gauges
Chris
PS when you raise the dash cover it looks like there are 500 ground wires under there