My speedometer jumps all over the place. Sometimes its just a few miles an hour sometimes itll jump 20 or more in either direction. Was wonderin if anyone has had this problem or know what might cause it. Thanks.

 

Never heard of that problem, maybe a speed sensor?

 

I thought about that. Ill look into it thanks.

 

Yeah when i'm trucking along either with cruise control on or just with my foot holding steady on the gas it jumps 1-2 m.p.h occasionally. I never really thought anything of it, but yeah i'd say there is a really good chance it's caused by the speedo sensor.

 

Thanks guys. Ill look at it tomorrow and see what happens then let ya know.

 

Well i replaced the speed sensor and it still jumps like crazy. Any other ideas.

 

I did a little research, here's what I came up with;


1. Bad VSS (VehicleSpeedSensor)


2. Bad tone ring in the rear diff. The OP in the thread that this link will take you to had the same issue you do, and he wrote thread on how to replace it, with pictures.
replacing tone ring with pics - Ford Truck Enthusiasts Forums


3. Bad PSOM (ProgrammableSpeedometer/OdometerModule). You'll find diagnostic procedures for this at the bottom of the OPs first post on the thread the below link will take you to.
'92-97 Speedometer (PSOM))

Good luck.

 

Im gonna look into the tone ring. If i replace it im going to put in a limited slip diff. Any opnions on the best brand of diffs. My truck is a f250 so what kind of rear end does it have? Thanks.

 

Two easy steps;

1. Go look on the inside of the driver side door jamb. You should see a sticker like this.



Circled in red is your axle code.


2. Now follow the link below. Once you find your axle code on the left hand side of the chart, the next column over will say whether it's limited slip, and then one more column over will show your gear ratio.

What rear end ratio is in my Ford , do I have positraction? - Drivetrain

Good luck, keep the thread updated.

 

Thanks alot. Ill keep you guys posted.

---AutoMerged DoublePost---

39 code axle. Open diff. 3.55 gear ratio ( kinda high in my opnion). Any advice on the best limited slip out there. And what kind of rearend do i have?dana 60?