I have a 2000 Winnebago RV on a Ford F53 chassis. Recently, I turned the vehicle off and found that the speedometer was stuck at 40. After opening the dash in an attempt to investigate the instrument cluster, it dropped back to 0. However, upon moving the truck again, it jumps back to 40. Once I accelerate up to highway speeds, It begins to work properly above 40. Now it sounds just like every other broken cluster post I've seen, but here's where it becomes different:

When I stop somewhere, and its still at 40, I can flip the dash up and it immediately drops to 0 and stays normal until I move again. It then works until about 10, then shoots up to 40 again, and stays there until I hit 40, at which point it resumes working. Once I get below 40 again, it stays at 40 until I stop and flip the dash up.

I assume there must be a wire crossing that I am pulling apart by lifting the dash. However, there is a mess of wiring down there, and I don't have a clue how to find where it is crossing, assuming that's the problem.

Before the problem was discovered, I made three electrical changes, though I can't imagine why they would affect the speedo.

1. I rewired the trailer plug. I wasn't sure why, but I had no power coming to my running light wire in the towing harness. I couldn't figure out why that wire was dead, so I just tapped one of the tail lights and wired the trailer plug.

2. I replaced my backup camera. The old Sony began to flash, so I just ran the new camera wire under the frame and behind the dash. I wired the monitor to the existing cables that the old one was connected to.

3. The chassis battery somehow died while driving. It was slow to start in the morning when we left, and about seven hours later, I shut the vehicle down at a camping world and when I went to leave, nothing. Somehow the battery was down to 6 volts, which I have never seen before. I can elaborate on the battery shenanigans if anyone thinks its relevant. Long story short, new battery and it started up and has been fine besides that speedometer thing.

Thanks for any help, Zack.

 

Take it by a parts store that reads codes for free and see if you have any codes, specifically a speed sensor code or any other codes.

 

I have the same problem on my 99 f250 5.4 220000 miles 2 wheel drive. It seems like when it rains my truck does some strange stuff. I found a puddle of water on my floor mat. The dome light would short out but be dim and make a buzzing sound near the fuse box. I sprayed air on every harness under dash and fuse box with battery loose. That fixed the dome light issue, not sure why. The speedo bounces when I hit 45 mph. The engine light is on. I have a fan pushing air under dash hoping that fixes it. Went to autozone it pulled a vss(vehicle speed sensor) code, it's not that. Sounds like there's water somewhere where it's not supposed to be. It was fine until it rained. The Transmission would Rev high and shift violently. I traced that to the passenger top harness on transmission, water logged. Sprayed it with air and it fixed the transmission problem. I got a nice stereo system and everytime it hits the speedo bounces. Alternator issues! It's the oem alternator. Autozone says it good. What do they know

 

There for awhile Ford had problems with windshield leaks. The water runs down on the inside of the firewall and gets into the fuse box and the GEM module. The GEM module is a circuit board thar controls a lot of stuff. If you take your fuse box apart and the module apart, you will probably find a lot of corrosion.

 

Thanks Franklin I will take apart the fuse box just to check it out maybe clean it. I guess I'm just gonna have to cover the cab up with a tarp when it rains until I can find the leak/leaks. I fixed the speedo bouncing. It worked for me unless something is really screwed up on yalls, this is easier. I took apart the dash, steering column and fuse panel, disconnected the battery and put a fan pointed up under the dash for 4 hours maybe longer. After that I put everything back together and the Check engine light is off, transmission shifts normal after I shot some air in the passenger side harness that plugs in the top of transmission(it shifted very violently before), dome light doesn't short out, speedometer needle is not bouncing. I hope this helps everybody. It worked for me. Like was Franklin was saying there known for leaks by windshield on bottom. Strange stuff. DC volts does strange things when there's water applied, if it finds a path to ground it's just like having wires touching. If that doesn't work, Might have to spend some $$. Good luck

 

Regarding my previous posts. I took apart all pieces where the windshield wipers are and cleaned up around the bottom window and where it's mounted(where the seals are) and I put a bead of clear silicone all the way across. Hopefully that will fix the leak causing all these problems when it rains. Everything's still normal on my truck. So my fuse box under the dash was water logged. Not good.





I ran the bead across the bottom of the windshield, all the way across. It was dirty gonna have to clean it. It's covered up by the panels. Can't even see it.

 

Zack, having same problem now. What was solution? Tom