As most of you may know, the speedo is most likely inaccurate.

I found this out on my fathers truck last week. We matched the digital one (by means of the odometer, where you hole the button, turn the key to just before start, wait for TEST, etc) to the analog one and found the analog (or whatever you call it, the "normal" one, was 3 mph fast.

Some of you should try this, and see how consistant it is.

 

Exactly how do you test your speedometer? Can you give me a URL or a quick rundown?

 

Hold down your odometer button, then turn your key to "on". Release the button when the display says test. You can then use the button to scroll through several different functions including a digital speedo.

 

By "odometer button" are you refering to the Trip Reset ****? I held that in, turned key to on (not start right?) and all I get is the check engine light. Is that where it's supposed to say test?

 

Yes, just keep holding it down, it will say it, and when it does, release it. Press the button down, release, etc till you get to ENG0000, which is the speedo. Start the truck

 

I'll give this a shot during my lunch break. What other tests can I perform?

 

Thats about it...

TAC shows RPMS
FUEL is in gallons

 

BadDreams I got bad news. You got to have a 99 or newer for this to work. sorry bud

 

Fast54,
I have noticed with every new Ford that I have owned from a 1986 Mustang GT to my 2001 Expedition that the speedo's are off like 2 mph fast. I was starting to wonder if this was a Ford ploy to make it seem like we are getting better mpg. (more miles on the amount of fuel) I kinda gave up on that theory when I checked the speedo on my '97 Louisville (dumptruck) and it's off 2 mph just like clockwork....

 

I've found that the speedo is off, but the odometer is right on, or even slightly long.

 

I have to disagree with the over estimate (for my truck at least). I have a GPS navigation system for my Palm and it registers exactly what my speedo shows with the cruise control on. What speeds were you testing? and are your tires stock? The HD tires are 275 45R20 and the spare is a 255 70R16. If I were riding around on four of the spare tires the spedo would read a half mph slower at 55 mph (actual).

Go to
http://www.c5-corvette.com/tirecalc.htm
They have an excellent tire calculator and they do calcs for 20" rims.

 

DAH! Oh well.. I'll just go back to my tried and true method for determining speed: Whats listed on the speeding ticket

 

You have to be careful with that. The last time I was busted the officer wanted to write the ticket to the tune of 85 but my cruise was set to 80. I was caught in a 4th of July radar (laser) trap but my old detector is dumbfounded to laser

 

All were new cars/trucks on new stock tires except the Louisville. The speeds were all tested with police radar, either the roadside test trailers (we have alot of them around here) or from squad cars (I have a number of friends on several different PD's).

 

both of my p/ups indicate 2-3 mph faster on the analog speedo. than on the digital....stock F1s on the L.............Dan