Speed sensor failure

There's a little bit of apples and oranges in your post, but I'll try.

The speed sensor is on the transmission, not the engine. Normally you'll see an erratic speedometer as the first symptom of impending speed sensor failure. But that's likely not the problem.

I'm not familiar with QC, but the ELDs (but not AOBRs) must interface with the ECM per the regs, and all of them that I've researched do that through the J1939 bus. See if there's a diagnostic screen on your QC, and see what it shows for the J1939 status. It might even show the values received from the ECM.

Since your not getting miles or odometer, my guess is you're not getting a link to the bus. A few of our Western Stars required a different harness with a couple pigtails to splice into bus somewhere other than the diagnostic plug. The bus is easy to find, it's normally a green and yellow pair of wires.

 

Those sensors are pretty cheap ~$40.

 

My Omnitracs does that every once in a while. It will record driving on the graph, just doesn't record the miles. I can hold the button on the side in and re-boot it, and it might not do it again for 2 months.

I have found it I manually change it to driving before I take off it doesn't do that. Only seems to happen occasionally when I drive off and it switches to driving on it's own.

 

I will try to find a picture. If you are facing the screen, it is on the left side. Pull the rubber strip back and it is under it, small square button. Hold it in until the thing shuts down, it will come back on on it's own. I never would have found it if not for the Omnitracs support line.

 

This is the one I have. That little rubber strip you see on the left side, pull it back and the reset button is under there. Small square button, hold it in for about 5-10 seconds until the thing shuts off.

Hope this helps..