Need help!! Freightliner with Cat 3406e got me stumped

Coolant level sensor supply comes out of thr vehicle harness it appears in your diagram, at pin 36. Just check it at the coolant level sensor with the harness connected, and at pin 36 of the ECM when you have the harness off.

You won't need to remove the engine harness

 

Ok gotcha. Will check it first thing in morning.

Ty

 

Ok

So i have 4.8v when key on at pin 36. That should be the coolant level sensor output voltage.

Now what?? Lol

 

I guess that means the ecm is turning on...just not communicating with the truck???

 

Update:

My trucks 40 pin plug has no j1939 connections made from the factory. Pins 36 and 33 have blank plugs in them.

I have j1922 and j1587 connections at pins 3 (.9v) and 9 (3.1v) and pins 1 (.8v) and 7 (2.8v) respectively.

 

That would be my assumption. Crank, no start, or no crank? I was assuming it would crank

 

Have you checked your 1587 datalink at the diagnostic connector, and battery pos and ground there?

You may have 2 seperate issues going on

 

I hooked my laptop with cat et to the dataport in cab and it connects just fine. I can read codes and see cslibrations etc...

I apologize but dont know tge difference between j1922 and j1587 how do i cjeck those??

The truck will crank...just no start and no CEL / ecm power on lights on dash

 

Ok. So your ECM is powering just fine, and your data link is working. Timing sensor would be my first check from there. Very common