Apparently my truck doesnt want me going 65+

[kc0stp]

Seems whenever I get around 65mph the speedo instantly pegs at 85, once I drop down to 55-63 it goes back to normal, any ideas what may be causing this?

 

[justinray]

I bet it's broken. That's my wag.
No, but mine did nearly the same for a bit, ended up being a bad instrument cluster, but I would definitely go the VSS route first.

 

[OLDBULL8]

1997 Mazda Miata (DD)
2010 F150 (Tow vehicle/borrowed)
1984 Mazda RX7 (Track only)
1995 24' Pace Shadow (Car trailer and garage)
1991 F250 -

Any idea which one of those is doing that?

 

[kc0stp]

1997 Mazda Miata (DD)
2010 F150 (Tow vehicle/borrowed)
1984 Mazda RX7 (Track only)
1995 24' Pace Shadow (Car trailer and garage)
1991 F250 -

Any idea which one of those is doing that?

Well lets see here, it involves a speedo so that eliminates the trailer, I said in thread title it was a truck so that eliminates the 2 Mazdas, this is the IDI message board so that means of the 2 remaining its most likley the IDI powered 91 F250, and another nail in the coffin for the F150 is that its speedo doesnt peg at 85 (120 would be pegged) so we can say with confidence that it would be the 91 F250

 

[f-two-fiddy]

Clean the VSS, prolly clogged up with gear shavings. The Ford VSS has been a known sore spot for years. THere have been numerous 'updates' to the VSS over the years. I don't think any have been much good.

 

[91idi]

Beings 91 its a cable speedo not electronic.cable or gauge is bad

 

[Jake_IN]

My truck doesn't do it but my 94 Explore does that. Its done it for about 4 years now. Its worse in the winter time when its cold. Never done anything to fix it though.