I have a 2001 Ford F 450 truck and I'm having a problem with the speedometer

When I'm fully stopped, the speedometer jumps to 20km/h when I'm holding down the brake. I let go of the brake and it goes to normal, I full brake again and it jumps to 20km/hr at a full stop. There is no revving at all either if it matters.

Could someone please tell me the problem and how to fix it? Thanks.

 

Sorry if I'm not getting it but if you're fully stopped, and you can obviously tell, your foot is on the brake...and when released it goes to zero as normal! Is there really a problem, or is it just a quirk? I'll try my '02 tomorrow and see if it operates the same, and post back

 

Is this a constant problem, or intermittent?

Is is always 20km, or is that value random?


As a first start, I'd have someone apply-release-apply-release the brakes while tracing the brake lines beneath the truck to be sure there's not some point of movement in the lines.

I'd also look to be sure the lines are corroded, and that there aren't any obvious fluid leakage points, and see if the master cylinder level is down.


I would have thought the speed sensor would be somewhere alongside the drive shaft. If you can find it, see if its loose?

Not to say this is an unusual problem, but if you don't find anything with your inspection, I think I'd be inclined to contact a priest and arrange an exhorcism!

 

Did you ever get this figured out? im losing my mind trying to find this issue on my truck

 

Trying to solve the same issue... any updates?