9282 M P H readout problems

[partimefarmer]

I recently purchased a 9282 4-wheel drive tractor the M P H readout in the cab is reading to slow, for example on the road the readout is 12.8 I put a portable G P S in the cab and it shows 16 which is correct, I have contacted 3 different service managers from different stores and all I have learned is possibly the sensors is bad so I changed that, you can calibrate them the range is from 20 to 50 when I first checked it it was at 46 then it was reading 11.4 on the road , so you see that was going in the right direction, but that is as far as it lets me go, one of the service managers told me to check my ohms at the sensor it should read around 1000 to 1200 it read 1240, all the service managers told me they would have to do some research and they would get back with me, I hear nothing where do I go from here? any ideas would be appreciated. THANK YOU IN ADVANCE

 

[partimefarmer]

Partimefarmer coming back with what I found out. my gear ratio reading was not set right, this is not the M P H calibration it is where the speed sensor picks up its reading off of the gear under the tractor it was set on 60 and it needed to be set on 30 so they told me I was getting a 50 percent reading. What we did was took the dash out and sent it to Ag Express and they reset it to the factory specs and its working perfect. Maybe this information can help someone else.