Speedo Going Haywire

[Burnproof16]

I just noticed the problem the other day when i was cruising down the road doin about 35 mph and the speedo just goes always to 120 for a second then comes back down to my normal speed. It only happens every now and then. Any clue why it's doing this.

 

[high toned sob]

What year truck? 4 wheel or 2 wheel? If it's 4 wheel, it's your speed sensor on the top of the pumpkin. If it's 2 wheel, it's in the tailshaft of the trans.
Where are you located? I have a extra one.
Thanks
mike

 

[Burnproof16]

It's a 98 4x4 12v
Located In Georgetown, Ky
That would be great though. I'd really appreciate it. How much