Speedometer needle malfunction

[NPdarkside21]

So after seeing a how-to on removing the green film on the inside of the instrument cluster, I decided to do it and ended up getting all but the speedometer needle back to it's original position. The strange thing is also, now the needle "jumps" between speeds and sometimes gets stuck between 20-30mph range. All the other needles return and move just fine. I tried "calibrating' it while the whole cluster was plugged in by turning the key and removing/adjusting the needle to sit flush. It sits just below 10mph (like it used to) but now it doesn't move fluidly like it used to. I'm worried I might have broken the gear that the motor/servo turns to gauge the speed. Any suggestions? '99 XLT 3.0L w/out Tachometer.

 

[RonD]

Never heard of being able to calibrate speed needle at 0MPH

You need to hook up the speedometer motor to AA battery, 1.5volts, and then adjust needle so its pointed at 70mph, then power off and on a few times to make sure it goes to 70mph each time

Use a new AA battery, because you were suppose to do this BEFORE removing the needle so you could see what it showed with that battery so when you put needle back on you would duplicate it
But I think 70-72 is about where it should be with 1.5volts

Pictures here: https://www.ranger-forums.com/general-technical-electrical-18/calibrating-speedometer-needles-134925/

 

[NPdarkside21]

Don't recall seeing anything about doing that BEFORE taking the needle off but thanks.

 

[RonD]

Doing it before taking the needle off takes the actual voltage of the AA battery you are using off the table, assuming you use the same battery to re-calibrate needle without putting it back in the remote and using for a few weeks, lol

The actual voltage is what puts the needle at a specific spot, so 1.3v, 1.4v, 1.5v, 1.6v would each show a slightly different MPH
Now any speedometer can have a +/- 5% error, thats industry standard for Ford and most car makers