07 Peterbilt 379 starter/relay problem

I had the same thing happen. On mine the wire running from the starter relay on the firewall had rubbed through about half way to the starter. It runs down with the same wire going to my oil temp sensor which was also rubbed through in the same place. The wire from the oil temp sensor was keeping the starter engaged.

 

Many thanks to all whom have contributed to this post. You've reminded me that there still exists a spirit of brotherhood among drivers and owner/operators out here.
At the Loves in Fair Play, SC at the Tire Pass fuel island unable to get the '05 Pete w/550 Cat to crank. checked and after some help from the light repair mechanic determined it is the solenoid on the firewall. We jumped it and for the total repair bill of ... $0.00, started the truck. If they are open today, New Year's Eve, I will pick up one of these solenoids at the next Peterbilt store.

 

First problem when this happened was the button the previous owner installed was tapped into the relay over on the firewall, they got rid of it and fts set up off the key to crank again the way it should be,. Got the truck back Tuesday 12-27-2016 and my mechanic said the starter might have just shorted out because all of the wiring looks fine. So the new starter was under warranty but I had to pay labor. The guy on the post underneath I seen made a good suggstion .
And as far as insurance, Ive been told most insurance companis dont cover faulty wiring but will cover certain thing that were damaged, didnt make sense. Ive got full coverage through OOIDA .

 

If it is a wiring issue, start from the beginning, not the middle. If the truck has any age to it then check to see if the + & - cables from the battery to the starter are “hard” or stiff to bend anywhere. If so, then you have corrosion inside them and this will cause solenoid failure and any testing “may have” resistance/interference. If you start with testing the starter you may miss this. Also have batteries load tested to eliminate a bad battery. By NOT doing this FIRST then you take a chance on voiding any replacement starter warranty. ✅

These cables are special order from Peterbilt and may take days to get OR you can make your own for around $180-$200. *379 C15* will need 14’ of 4 ohm cable, (75”/1900mm length for - cable and 90.5”/2300mm length for + cable) 2 battery connectors, 2 starter connectors, some red and black shrink tubing for the ends, and reusing the old cable plastic protective casing. Making them yourself requires a way to cut large wire evenly (pneumatic cutting wheel works best) and a hammer crimper. Hope this helps.