Turn Signal relay location on a 2013 Petrbilt 386 (2024)

Good Morning Ladies and Gentleman,
Here is the long and skinny of it, My clutch went out at 400K I was working local so i limped the truck into the Peterbilt dealership. a week later Ta Da!!! new clutch. Buuut Noooww NO Turn signals on the tractor, No 4 ways on the tractor, the Only turn signal that is working is Passenger side trailer....head scratcher?!?
The only thing I can think of is maybe there is a harness that got unplugged next to the trans or is there a relay that i can check somewhere.
Thanks
Kevin

Ok Now remember I have: a 2013 Peterbilt 386 with a PACCAR motor and an Eaton 13 speed trans and 400K on the clock I checked and cleaned every single fuse, checked every single relay,
Then moved to the inside of the cab and removed the kick panel and checked all the fuses....all were good.
I tried to reset the code by cycling on -off with the key. I even looked behind the glove box like one of the service guys suggested for a a 3rd fuse box. On my 2013 Pete 386 there is NO 3rd fuse box behind the glove box just:
1. under the hood/driver side
2. under kick panel/ driver side
3.under the bed in my sleeper/driver side
Thats is IT for fuse boxes
everything else was in working order head lights. tail lights, brake lights.
So as I was about to give up and call a mechanic, I decided aww what the heck, so i grabbed my creeper out of the pick up and went under the truck to see if there was a cut wire/harness etc. I started at the duals and started working my way towards the transmission, checking the wires as i went. I made it to the drive line yoke at the rear of the trans/ driver side frame rail just before the or after the Bendix air dryer there is a small box that has two harnesses plugged into it I noticed that one of the harnesses that was not plugged in all the way and the plastic locking cap/ring was in the up position. So i reached up pushed the plastic lock and harness seated and plugged in. I almost couldnt believe my eyes I so excited that scurried my fat ### right out from under the truck and hit the 4way switch and all my turn signals and 4 ways were back in operation. Man... I was stoked!! Fixed it meself! I will get some better pix later on if people are interested in seeing what it was that was messing with my truck. Maybe this will help someone out there because im SURE im not the 1st guy that this has happened to.

As I was reading I was going to mention that box on the frame but you findered it.

Any chance you could send a better picture of the location of where the wires plug into? I have a 2013 pete 386 with a isx Cummins,eaton 13 speed. Ive lost turn signals on right side of cab, although the rear right signal works. All other lights and flashers work. Thanx

Is the LR turn out on the rear? Check the G4 fuse underhood fuse box. All of the "g" fuses are for lighting. If the fuse is good and power to both sides you likely have an open wire between the underhood pdc and the chassis node. If the LR turn is working you have an open wire in the chassis harness after the node or between the node and the lights.

Yes as a matter of fact the drivers side rear turn signal is out but all the other drivers side signals work. I will most definitely check that first thing in the morning. I appreciate it very much and I will update you after I check it.

Turn signal powers are diagonally split between fuses. Just the opposite will happen if the other fuse blows. LF and RR turns will be out together. Paccar set it up this way to keep a signal working on one corner of the vehicle in case of a short.

The same holds true for headlights. In case of a wiring short, you will lose left high beam and right low beam together. Never both.

Goodysnap, partner you hit the nail on the head. I got to work this morning and first thing I did was pull that g 34 fuse you had mentioned,and boom turn signals once again. Sir, I thank you very much for your info. Saved me alot of headache.

Take a close look around the harness's as you likely have a wiring rub somewhere. The fuse didn't blow for no reason, ya know? Time will tell if it blows again....headlight harness around the hood pivot area and tailght area at the rear crossmember are the most common spot. Course dont rule out the trailer and 7 way cord too.