[78toyFJ40]

I know, I know, you are all thinking why was this guy taking a picture of his instrument cluster while going 110 mph!

Well the truth is if you look at the tach there's no way I was giong that fast...well, I guess the fact I have a 3FE is a pretty good clue I wasn't going that fast!

Here's the scoop, yesterday my speedo started to make a buzzing sound, this morning it made the sound but then the needle jumped to the other sided of the dial. It jumped once I exceeded about 40mph, then it was bouncing all over the place.

Has anyone else seen this happen? Are there some little plastic gears in there that are either stripped or have come loose? Maybe something to do with the cable...seems like the opposite would happen if it was the speedo cable...but I haven't had a chance to tear into it yet to take a look.

[Ebag333]

Check your speedo cable and connections. Your truck is running oversized tires, do you have an adapter to correct the speed?

[ginericLC]

Were you driving between Snowville and SLC? Mine does that all the time in that area on those hills. What is crazy is the GPS says the same thing!

Check your speedo cable at the VSS.

[CJF]

Cool pic.

[jonheld]

Woa. Slow down big fella.

If your speedo was making noise prior to the excessive speed, then I'd bet on a bad gear in the speedo itself. FJ80 is all mechanical from the transfer output to the speedo. I don't think there's any way the speedo drive gear can do this, but it's been a while since I had mine apart. The cable is...well...a cable.

The only other possibility I can think of is you don't have a rear driveshaft, you were driving with the center diff locked in front wheel drive and you unlocked the center and hit the accelerator. This would cause the rear output shaft to really move and indicate a rediculous speed.

[JollyGreen]

if it works fine until 40, I guess a bad speedo.....