Hello, on my 2007 peterbilt 386 I had several things quit working The other morning at 1 time. My blower fan quit my window controls and power mirror on my driver's side Door and my aux lights.(lights along bottom of cab and sleeper). The other switches that are directly right of my steering wheel, such as cruise, engine fan And so on all work, but they do not light up. My check engine light also came on at the same time which seems odd.
I've cleaned up battery connections The low voltage disconnect and i've checked all the fuses and relays in the fuse box by the driver's side door. Any ideas of where to look to next? TIA
Electrical problems peterbilt 386
Discussion in 'Ask An Owner Operator' started by Dwight Goertzen, Feb 21, 2026.
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Update. I found 2 rows of fuses that dont have power to them. Followed the power wire from said rows and there's 5 wires that are spliced in a heat shrink down to one main power wire. I can follow it up behind the steering column by the firewall but can't tell where it goes after that. Anyone able to tell me where the power wires from the fuse panel come from?D.Tibbitt Thanks this.
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Which fuse box is it? Guessing the one on the floorboard? If so the main power wire should run out of the firewall into the engine bay, and be getting power from something else. eventually getting to the batteries in some way. Take some pictures if u can
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Thanks for the reply. Yes it was on the fuse panel by the driver's side door. After a bunch of testing and messing around I somewhat accidentally figured out one of the relays(main accessory relay 70 amp) that are right behind my instrument cluster was sticking. I put it back in after testing it and everything started working. I got a new one on hand now but everything is working fine so far!
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