2015 International Prostar TCM not showing up in the line up

Why are you r batteries draining?

When it sits for a week, what is the voltage at the TCM with the key on?

 

@Heavyd hangs out in the International forum International Forum
Usually on the weekends though, he may be able to help. You might read through the International forum to see if there is anything relevant to your problem.

 

I would say you have bad main battery positive, ground, ignition or datalink feed to the TCU connector. Next time the TCU is not communicating, remove the OEM connector at the TCU and check the following;
Pin 35 - ignition input (key must be on) 12volts
Pin 38 - main battery positive 12 volts
Pin 36 - main ground
Pin 2 - 1939 datalink - 2.4 volts (approx at key on)
Pin 3 - 1939 datalink + 2.6 volts (approx at key on)
At key off, you should have about 60 ohms of resistance between pin 2 and pin 3 to also confirm if your datalink is good. Main power and ground should also be load tested with a headlight bulb to ensure the wire can support good amperage. If all this is good, your TCM is faulty. Low voltage cranking will take them out.

 

@Heavyd I believe I have this same problem.. Batteries ran low tried cranking, slow crank then nothing... Message on dash *ELECTRICAL FAULT* ....I replaced the Batteries and same message appears, and still no cranking.
How do I get to the TCM.. I have no lift or jacks to get the truck up in the air. Is it accessible through the battery box or from inside the cab.

 

The TCU is mounted on the left side of the trans. From underneath is your best access.