I own a 2004 f150 5.4tritan lariat, and the speedometer would go up normally and then gradually fall all the way to "0" while driving 60. Now it does not go up at all. Every once in a while I will look down and its at 20mph at freeway speed. Any ideas?? Thanks

 

I have exactly the same problem on mine, same truck. Same specs. Did you figure this out? If so, what was the fix please?
I have been given about four options. LoL
One of which is instrument cluster which I doubt and do not want to do. I suspect its the part I just bought, a speed sensor, which supposedly goes in the top of the rear diff...
I would appreciate hearing what yours was please. Thanks!

 

The speed sensor in the rear axle is for the ABS, the speedometer should come from the transmission "Output Shaft Speed Sensor". If any of the speed sensors were faulty, I'd expect to see other symptoms such as erratic shifts (or ABS activation/light for the rear axle speed sensor.) If you have a scan tool that can read PID's, there is a vehicle speed PID you can monitor while driving to see if the issue is on an input to the PCM. If the Speed PID seems correct, then the issue is on an output from the PCM. The PCM send the vehicle speed to the instrument cluster over the CAN BUS Module communications network. If there was a problem with the CAN BUS, I think this would also cause a fault code and some other gauges would be non functional (this would include the tachometer, does the tachometer work?). Any other issues with the Instrument cluster? Does it have a check engine light or flashing Overdrive off light?
I suspect either broken solder joints in the instrument cluster (common on other vehicles, haven't heard it being an issue on the 04+ F150's) or a failed speedometer stepper motor. You can disassemble the IC and try to repair it if you feel comfortable or you can replace the entire IC. A replacement instrument cluster will probably need to be programmed by a dealer so you can get them to diagnose the issue as well if you go that route.

 

I think that is where your gremlins are. My "brake" light has been on for years. No problems with the brakes what-so-ever. Sometimes I hit the right bump, and the light goes off for awhile. I've seen videos online where guys actually took their dashboard apart, then wiggled stuff around, and the brake light turns on & off. I almost want to believe that those wires back there are old, loose, and have poor contact. Same way the guy in the video just touches the wire harness, and the problem is fixed.

 

Hey guys,

I just wanted to chime in really quickly and see if we could be of any help. We repair these clusters for both failing gauges and for the brake light staying on, so we would love to be able to help you out if needed. I would follow Shadow's advice for the speedo though. If you are seeing the correct speed signal through communication lines then it is likely a issue with the speedo motor, but if you are not able to read that data then I would look elsewhere on the truck. I have included a link to our website for the repair just in case you need it. Please let us know if there is anything else we can help with.

https://circuitboardmedics.com/2004-...-light-repair/

 

Thanks for the infor. Now that I browse your website, I see other things that you can help with.