Temp gauge does not work-tach is throwing an SLF-13 code. Sent in to Ag Express twice and they find nothing wrong with it but does not work for me. I tried running new wires from tach down to sensor but did not help. I put a new sensor in but did not work. I put tach in different tractor and still throwing same code. I go under "display info" in tach and temp is reading negative 83 degree F. Is there something else you guys can test?