No Speedometer 2013 CXU 613 Mdrive Trans

[HoneyPot]

Hello all,

I am writing this thread because I am at my wits end...

I have a 2013 CXU613 day cab with an MP7 and MDrive trans. 

All 4 corners of the wheel sensors show the correct speed, abs functions normally, all modules test fine. Issue I am having is the speedometer shows double the speed the truck is going then cuts out all together. Stop the truck for 5-10 seconds(still running and in gear) it will restart and show double the speed etc. It won't go above 14-1500rpm while in gear, which to me says vss is losing signal to vecu.. My issue here is, it is a brand new VSS, brand new tail shaft/output shaft with pressed on tone ring, brand new VECU top plate. I have checked the grounds under the dash, the passthrough conenctor on firewall, removed harness from truck/trans and tested on the bench(read resistance to see if any fluctuation while wiggled) and I have yet to find the culprit. The only active code I have is PSID 211 MID 219 FMI 9. Data Link Abnormal update rate.

I get codes SPN 84FMI 19 and SPN 84 FMI 9.

Please help, I have been trying to figure this out for days...

[Joey Mack]

Here is my shot in the dark... Years ago i chased a similar issues in a CXU.. i found a cut wire in the harness that goes over the frame rail on the drivers side, under the cab.  It went to the transmission. Fixed the wire, and it fixed the truck..