new speed sensor truck won't start?

[hosetrucking]

Thanks Waterloo, I might have to give that a try lol.

[Waterloo]

Don't laugh... LOL!

[bazdan902]

I doubt the sensor has anything to do with your issue but you have disturbed something. Maybe have to find where in the firewall harness your ignition switch runs too, make sure it's getting power could even be the switch for that matter.... If your pass through firewall connectors have any Green or look questionable at all you may want to start cleaning them up. Very strange things can happen very suddenly.

I lost dash lights and tail lights on truck and trailer a few weeks ago all of a sudden, worked one day then the next I had nothing. I sprayed everything down with an acid based terminal cleaner and got everything working again. When I got home took apart the plugs, nothing rotten but just a little green is all it took.

[hosetrucking]

Thanks Waterloo, yes I've fixed many of things with a tap, bump, and sometimes a flat out hit. Lol. Can't hurt to try.

Bazdan, yeah I cleaned the terminals at the firewall box but will try it again. Also I'll double check to make sure I didn't disturb any connections near the starter. Tomorrow I will put a multi meter to it and hopefully track down the problem. Will notify when I get it fixed. In the meantime still open for any and all suggestions. Also on voice recognition so please excuse any typos. Thanks

[Rawze]

(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.

[bwake]

The first thing I'd do is check the signal wire at the starter solenoid. See if you have 12v there when the key is in the start position. If so, you have a faulty stater solenoid or bad ground at the starter solenoid and it will need to be replaced/repaired. If not, you'll need to see if the stater relay is working when the key is placed in the start position. This can all be checked through the relay with the meter set to amps and jumping from pin 30 to 87. This is using the meter as a jumper wire so the truck should start assuming there is power at 30 and no breaks in the wire (pin 87) going to the starter solenoid. I doubt these two are connected and just crazy timing.

[hosetrucking]

Figured out what happened, when I was routing the new wire down near the starter and then back to the end of the transmission my hand must have disconnected another wire connector. It's was buried and just luckily happen to see it.

On a side note, when I took out the Speedo sensor on the back of the transmission the sensor plastic housing broke off inside. Instead of taking off the rear yoke assembly I was able to take a mini butane torch with a 90 degree head and slowly burn and pick the plastic peices out with some long skinny needle nose pliers and a mirror to see inside the plug hole. Turing and annoying to perform but took only 30 minutes versus an hour or two wrestling off the driveshaft, yoke and rear transmission assembly. I did this on a truck with a lot of grout clearance and no crewmember, exhaust, or plumbing in the way. Hope that helps someone.

[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.