Peterbilt 379 no cab power

Do those years still have the 2 ignition relays on the left side behind the cubby hole on the dash?

@wore out? I dont know who here has a later model 379.

 

2 big wires and 2 small?

 

I honestly haven't worked on one of these later dash style 379's, FYI. I'm going off what I've seen in the older ones.

Either way, no power to either side of that relay? If not, Just for S&G, check for any broken mid sized pisitive cables at the alternator, starter, and in the battery box.

 

Need a Peterbilt 98 379 wiring diagram

Try Supermiller for other schematics. I have a few.

The relay behind the ‘A’ panel (Marlboro cubby) is the accessory power relay.

Why am I thinking there’s a power wire dropped down behind your batteries or battery box that got left off? If you replaced all the battery cables.

 

I had no power for anything Thursday morning but it was a broken end on my ground cable for the starter. It was the thick cable from the battery box to the starter. I had to use jumper cables to get it starter.


This was on a 04 Peterbilt 379 with a CAT. I'm not saying that is your issue but it's what happened to me.

 

If you had power messed with it then no power go back where you messed with it.

 

Hell, how did I miss the part about having replaced the battery cables?