Speedometer Reading Way Off?

[robo44]

Thanks for the great knowledge & Feedback... Ford will be taking a look at it an i will report back !!!

[PenJoe]

Unlike the old gear driven speedos, the new speedometers can be calibrated for different tire size, etc.

Years ago, I had a Pontiac with a 3-speed auto trans. I had it changed out to a 4-speed auto trans. I was on a two-lane road between cities heading for a reserve meeting. I came up behind this county sheriff on a two-lane highway.
By my speedometer, he was doing 40 MPH. So, I passed him. And so, on came the gumballs. He indicated that I was driving 15 miles over the speed limit. A total surprise to say the least. I explained my speed and questioned, would I be dumb enough to pass a marked squad car and be asking for a ticket? Being reasonable, he asked if I had changed tires or made a change to the car. Yes, I changed transmissions. He gave me a pass and then drove ahead of me to indicate when I was doing the proper speed limit. The speedometer was off and I had to change the gears on the transmission. It's a lot different today.

[rockfordroo]

Originally Posted by formerFR

time it between milepost - if you hit a mile in 1 minute, then you know you're traveling
60 miles per hour

Originally Posted by n0ms

This is the correct test. Reset the trip odometer also at the start. Math doesn’t lie .

But DON'T use the odo to determine your mile. If the speedo is off, the odo will be off, too, as Bluepill said in Post #10.

Use an interstate that has mile markers, or find an actual test area.

[Frameman]

Use a gps . It will give you an actual speed reading as you drive .

[Frameman]

Almost all ford trucks are off 3 to 4 mph ! If your speedo says 50 you are probably going 47 !

[5er_tom]

Both of my Ford trucks speedometers are spot on compared with the Garmin.

[robo44]

Appointment is this Friday will report back what is at issue. Thanks for all the feedback

[robo44]

Just wanted to follow up on this. Just FINALLY found a Authorized Ford Location that would work on my FR3 Warranty. Took them about 2 bourse but did find out that the axle and tire size was not programmed correctly. They fixed the issue by reprogramming. No cost ...

[Chuck_S]

These Ford settings (and many others) are accessible in the computer via the OBD2 port, a $25 data connector, your Windows laptop, and free Forscan software. A surprising number of things are controlled this way and each chassis model is different so ya gotta know what addresses to change. F150/Expeditions are fairly well documented and I suspect the motorhome chassis have been worked out by not too.

On my '17 Expedition I activated DRLs, extinguished excessively bright fog light indicators on the dash display, and added engine hours/idle hours to the dash display. The F150s can be set on some years to show individual tire pressures and other items. Worth exploring of you have a Ford chassis.

-- Chuck

[Mr Towed]

Originally Posted by Chuck_S

These Ford settings (and many others) are accessible in the computer via the OBD2 port, a $25 data connector, your Windows laptop, and free Forscan software. A surprising number of things are controlled this way and each chassis model is different so ya gotta know what addresses to change. F150/Expeditions are fairly well documented and I suspect the motorhome chassis have been worked out by not too.

On my '17 Expedition I activated DRLs, extinguished excessively bright fog light indicators on the dash display, and added engine hours/idle hours to the dash display. The F150s can be set on some years to show individual tire pressures and other items. Worth exploring of you have a Ford chassis.

-- Chuck

I'm going to look into this for my F-150, I know there are some settings i'd love to get my hands on without going to the dealer. Any specific cable you recommend or is just an OBDII to USB?

[Chuck_S]

I prefer a wired connection so I bought the OHP ELMconfig Forscan OBD2 Adapter. <--- that's a link. $30, not $25 (sorry).



Lots of Forscan information on the F150 forum(s). Speedo correction is a common one.

Download Forscan and register (free) for the extended version so you can change more things than just the few in the standard version.

Forscan is a Windows only program (to my knowledge).

-- Chuck

[Mr Towed]

Originally Posted by Chuck_S

I prefer a wired connection so I bought the OHP ELMconfig Forscan OBD2 Adapter. <--- that's a link. $30, not $25 (sorry).



Lots of Forscan information on the F150 forum(s). Speedo correction is a common one.

Download Forscan and register (free) for the extended version so you can change more things than just the few in the standard version.

Forscan is a Windows only program (to my knowledge).

-- Chuck

Cool, thanks, if that one works for you then that's the one I'll get.

I've gone a long time without a windows computer but my wife and I both have one that we needed for programs at work, so I can finally use stuff like this.