2004 Mack cx613 low power with road speed fault

[Littleitchy]

Speaking of Speedo problems, I have 04 Mack, one day Speedo worked next day only works at 50%. New speed sensor, checked tone ring and yoke tight and clean even swapped dash cluster from another truck still only works at exactly 50%. Cruise works as long as I get over 35 so 70+mph. Don't have much hair left too pull out. LOL!

[Hot oiler]

I have a 2009 Granite GU7 w/MP7. I am having an issue with the Speedo randomly dropping out which cuts power. If stop & kill the truck & wait for all the instruments to turn off then start back up the Speedo then works until it randomly does it again. The fault light does not come on. If you are going down the highway when this happens I can just turn the key off until all instruments turn off then turn back on & it returns to normal until next time. 

Very random - 5 minutes, 15 minutes or maybe even 45 minutes apart. 

[Frankg84]

Hot oiler, did you ever fix the problem, Im having the same issue 

[Shoez]

I had a similar problem with a 2000 CX613. Fault light would come on, truck would reduce speed until fault code reset. Initially just had dealership change settings to Not Reduce Speed with fault code, after which when fault code appeared truck would run as fast 80+ as you were willing to drive it.

Eventually we replaced the Speed Sensor wiring harness and the fault codes have not come back.