379 turn signal problems

Discussion in 'Peterbilt Forum' started by HammerTransport, May 26, 2021.

  1. HammerTransport

    HammerTransport Bobtail Member

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    Feb 28, 2020
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    Ive been chasing a turn signal issue for weeks. Originally it popped a right turn fuse. I replaced the fuse and it was fine for 2 weeks then blew again. Ever since it has blown instantly. If I’m sitting at home on a very rare occasion I can manage to get the signal to work fine no issues. When it blows it kills the right brake light on the tractor as well. But the brake lights work fine if you replace the fuse and don’t use the turn signal. I pulled all the turn lights off found no issues. Unplugged each one individually looking for a short in the light itself. Found nothing changed. I pulled apart all the wiring at the back. Nothing there. Looked along the frame rail. Didn’t see anything to the eye that would be a problem. I checked the column from top to the bottom and found nothing. Wires behind the fuse panel look good too. Sometimes what it will do instead of blowing a fuse, if you turn the hazards on it will flash the left side and flash the right side (on the dash only) once every 30 seconds. Then goes back to blowing a fuse later. The truck has had other minor electrical issues as well such as the sleeper blower motor turning on even if the dash is off, a minor back feed into the sleeper ceiling light on occasion, and when I first bought the truck the radio and cb and auxiliary lights on the side used to shut off randomly on the road but wouldn’t kill the motor. So idk if these are all related or not but I’m most concerned with finding my turn signal issue. Peterbilt says there’s no relay or flasher for a 2007. Just the module above the radio and the switch on the column. I’d gladly replace a switch if that was the problem but would the switch really make it blow the fuse when you use the hazards but not touch the turn switch itself? Any help would be awesome guys.
     
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  3. FLHT

    FLHT Heavy Load Member

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    Signal Stat worn out ?
    Take it off and take apart and clean it up inside .
    Try using new dielectric grease in it
     
  4. HammerTransport

    HammerTransport Bobtail Member

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    Feb 28, 2020
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    The what? Where would this be? *update* the turn signal is doing exactly what it did last time I unplugged lights. If I unplug lights and then after putting them back together it will only flash left side and right side will flash on the dash only every 30 seconds. After sitting all night (same as last time) signal worked fine. Didn’t touch anything between. Then drive down the road and try it, blows the fuse. Other times it will just blow the fuse right away when sitting. It seems if I unplug the lights and plug them back in then it changes what it does. Almost like it doesn’t sense a complete circuit until hours after
     
  5. FLHT

    FLHT Heavy Load Member

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    Aug 2, 2014
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    The little handle some use to signal a lane change.
     
  6. lester

    lester Midwest's #1 Feed Hauler

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    All lights work? Have you taken the trailer light cord apart and checked the ends for corrosion or bare touching wires? Could be in your turn signal switch on the column. And check the wires where it tilts and telescopes. When its working fine start wiggling wires. Frustrating I'm sure
     
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