94 Winnebago Adventurer speedometer

[JordanRAdams]

All of a sudden, a few minutes after I set out, with no warning, my speedo started reading ~20 mph over road speed. At first it jumped around a little, but then it settled and had been reading over consistently. I didn't change the tires or anything like that. It shifts fine and I didn't notice anything else off over about 90 minutes driving. I looked at the fuses and none seem to be burned out. I disconnected my battery, but I'm hooked up and won't be leaving until tomorrow. I've seen so many things it could be, but I'm leaning towards the speed sensor. Anyone have any tests I could perform, I'm somewhat mechanically inclined but I've never had experience with speedometers. My odometer appeared to function properly.

[Jim_HiTek]

I believe that a '94 will have the CAN system which is a system where you'll have sensors like the speed sensor, temp, oil pressure, etc., wired to a box that sends a signal up to the dash for various gauges. This is a lot of wiring if they were wired individually so the CAN system multiplexes the signals so there aren't so many wires.

When gauges on the dash are jumping around, it often points to a poor or corroded connection somewhere between the sensor and the dash. So yeah, first check the wiring at the speed sensor, remove and spray the contacts with contact spray, but while you're under the RV, follow the wiring up to the CAN boxes, remove clean and spray the contacts, then follow the bundle of wiring to the dash, unplugging spraying and replugging every connector you find. My '94 Bounder had a large plug under the RV around halfway between the CAN controller and the dash which had lots of corrosion on it. After I'd sprayed and cleaned that connector, the bouncing speedo settled down. But your RV many not have a connector under the chassis.

Anyway, cleaning and spraying connectors (and putting dielectric grease on it to prevent future corrosion) usually is the simple fix. You could have a bad speed sensor of course, but cleaning and spraying the connectors should be the first step.

Since your rig seems to be a gas, shouldn't be that big of a job tracing the wiring from the dash on.