MUDWHISTLE
Diesel Lover
How does one recalibrate the speedo on a 92 73 diesel rig? I'm running 36's and it is a ways off? thanks Lee
How does one recalibrate the speedo on a 92 73 diesel rig? I'm running 36's and it is a ways off? thanks Lee
how do I do this procedure? so what does this wire do?
First you want to get a rolling measurement of your actual tire height:
* Mark the ground and your tire and roll forward three revolutions marking the ground each time.
* Measure the distance from the first mark to the last mark
* Divide that number by three to get the average length of one revolution (this will protect yourself against a bad reading using just one revolution).
* You can then divide the length of one revolution by 3.14 to get actual tire height.
Next you figure out the calibration code:
The Ford calibration equation is: 20186 / tire height in inches = some number, then some number /.6666 = program code.
* Start with 20186
* Divide by actual tire size in inches
* Divide again by .6666
Last you enter the code into the truck:
To set the calibration, ground the single wire connector under the glove box that says PSOM (Programmable Speedometer Odometer Module). There is only one and it has a spade type plug on the end.
* Next look at your speedometer while sitting in the drivers seat and there should be a "reset" button and a "select" button.
* While holding the "reset" button in turn the ignition to "on" then let go of the "reset" button.
* The speedometer display will sweep once and will show a code. Now push in the "reset" button again and the existing code will be displayed with RECALL.
* Now you enter your new calibration code by pushing the "select" button until it gets to the new calibration code number.
* You may have to push "select" a whole bunch of times until you get to your code. If you turn off the key at this point the original code will not be changed.
* To store your new code press "Reset", turn off the key and unplug the ground wire under the glove box.
Don't forget that you can only change the calibration 6 times without replacing the module and the previous owner may have already had it done a few times.