I have 31's on my truck and the speedometer is about 3mph off. I've heard that having the speedometer off can mess with the tranny. Is that true? Is there any reason I should get it recalibrated?

 

3 MPH off at what speed? If it's 3 MPH off at 60 you won't get a whole lot closer. If it's 3 MPH off at 20 that may be a different story. Someone else will have to answer your questions about recalibration.

 

Yes it needs to be re-calibrated
Instructions have been posted numerous times. do a search.

 

http://www.ford-trucks.com/article/i...ND_BRONCO.html

 

My speedo is about 3mph off at highway speed. It says 75, a GPS unit says 72. That's not unusual, my old truck had the same error and that had stock size tires.

 

In some trucks, I know my FX4 can do this. Shut the truck off, and hold your trip/reset button. While still holding the button turn your key on to accessory. Your mileage display should then say sweep gauges. You can then scroll through and get a digital read out of your tach, miles an hour. Thats how I figured out im about 2 miles an hour off.

 

It does it at all speeds. Thanks for the link.

 

Does anyone have the DLC schematics? It says I need to put a metal clip into #567 on the DLC.

 

It also says it's the light blue wire with the yellow stripe.
Ford conveniently leaves that circuit out of the EVTM so I cannot tell you which pin it is so just look for the wire

 

Well, I think I screwed it up. I put it in the pin and got it on a ground it sparked and now it won't do anything. All my gauges and work but I can't get it to recalibrate. I can get to where it's calibrated to now, but no further.