new speed sensor truck won't start?

[DVT873]

(02-05-2019 )Rawze Wrote:  

(02-04-2019 )hosetrucking Wrote:  ...
now the starter won't turn over whether the sensor is plugged in or not
...

The engine computer has no way of keeping the starter itself from engaging on most trucks. The starter bump circuit is typically only hard wired through the ignition switch, ignition relays, etc.

-- If the ECM itself wanted the truck not to start...

A). you would have a red check engine light on.
B). The truck would still turn over,.. it just would not fire off and run.
C). You could see why by using insite or other diag. software.

On a truck with an auto-tranny, not sure tranny can prevent it from cranking at all, I would suspect maybe tranny can prevent it if the XY was stuck engauged?. Have not looked into it before.


-- Also, no, there is no special programming needed when you change that sensor. In fact, the only thing that requires software on the 2350 after a replacement is the turbo actuator calibration, or the DOC/DPF system needing a reset after being cleaned out/replaced.

FWIW on a Navistar with an Allison Electronic trans engine ECM has to see a system voltage signal from the trans ECM confirming neutral. If it doesn't, no crank. Have had a few broken wires over the years. The real fun is no codes because there is no crosscheck. Eng is waiting for it, trans has sent it but no 2nd layer of com to say the signal never got to the engine. Besides not cranking. Not sure about other makes or trans with X Y shifters. I do know that the neutral signal is standard Allison out put.