Situation: 2001 4x4 f250 w/ a 7.3. New to me. Speedo worked fine on the test drive and on the way home. Second day I owned it I found the batteries dead and needed to jump start it. Speedo still worked. Brought it in to the shop and put it on the charger. When I went to start it I turned the amprerage up to 225 on the charger and turned the keyand all the relays under the steering column clicked for a couple seconds. Tested the batteries and found both to have bad cells causeing low voltage. Ever since the speedo sits at about 70mph at a stand still and goes down 40mph when accelerating. I've already replaced the vss on the rear end because I was told failure is common. No change. I already asked in the towing forum figured there might be a little more ford guru traffic in here. Thanks for any input.

-odometer works
-cruise control works
-no codes or lights

-I know that the speedo can be calibrated for differant size tires from the factory, is there a chance I wiped out the calibration?

If the odometer works and the speedo dosen't it's more than likley a bad cluster. If I were testing it I would test drive with a scan tool hooked up to test the VSS system.

If the odometer works and the speedo dosen't it's more than likley a bad cluster. If I were testing it I would test drive with a scan tool hooked up to test the VSS system.

x2, most scanners can view the speed sensor input. Helps a lot with testing them. If your VSS shows the correct speed, its the cluster. Some have the PSOM you can replace, but im not sure if that truck does.

some bom speedos can be damaged by having to much voltage ( spikes ) - but i dont think you could have hurt it as a 7.3 needs almost 1200 cca to spin fast enough to start. so 225 amps shouldnt have hurt it -

if the od works, then the bom module or the speedo head is damaged. but as you say the cruz works i would say speedo head.

Scan tool shows proper speed. What is the psom? bom?

Programmable speedometer/odometer module. PSOM. Im not even sure if that truck has one. Im betting its the speedo.

I agree its prob the speedo, I think its going to be the whole cluster though that you would have to get. I don't believe you can get the speedo circuit seperate.