04 379 pete, deciphering the switches on the back of the speedo

Ok I am running a 04 379. The speedo and odo are consistantly off. Meaning that my speedo reads more then 3 mph faster then my actual speed even with new drives installed. As the tires wear then the speed goes even farther off kilter.

I have had it into Cat and Pete and they both say that the proper coding is in the computer for the axle ratio, transmission and tire size.

I had the dash apart the other day to put in a bulb in the speedo and noted the switches on the back of the speedo. I heard it had them but I never seen them since this was the first time I had the dash pulled down.

Is there someplace I can look to find the settings of these switches and can they be adjusted to bring the speedo down closer to my actual speed?

 

Got it figured out today. I pulled the speedo strap so that I could get to the speedo.

I picked a deserted road and flipped the far right switch to see what happend. Speedo needle dropped about 20 mph. I flipped the far left switch and it hardly moved at all. maybe a tenth of a mph. It took me three trys to get the speedo almost dead on. At 65 on the gps the speedo needle sits directly over the 65 mph line. At 68 on the gps the needle is just slightly below 70. At 25 on gps the needle is directly on the 25 mark.

Before with my foot on the floor the needle would run right between 70 and 75. Now it just barely touches the 70 mark which is GPS indicated 69.4.

Thanks for the comebacks on this.