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Electrical Gremlin

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 86dieselburb, Dec 21, 2005.

  1. 86dieselburb

    86dieselburb 1/2 ton status

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    Having a slight fuse problem. Seems the fuse that works the tailights blows out when the motor is running, with the lights on. Gauge lights go out with this fuse also. But will not blow out if the truck is just sitting with the lights on. Seems odd that it will only blow when the motor is running. Anyways just thought I'd ask to see if anybody else ran across this kind of problem. Not really that keen on electrical diagnosis.
     
    Last edited: Dec 21, 2005
  2. lamberthkp

    lamberthkp SITFU Premium Member

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    yep dont like those gremlins,
     
  3. tch777

    tch777 1/2 ton status

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    Check the alternator and voltage regulator maybe it is overcharging or surging.
     
  4. Stratispho

    Stratispho 1/2 ton status

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    Wire wearing through that gets moved when you put it into park causing a short??? sounds really odd
     
  5. outsider223

    outsider223 1/2 ton status

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    Before you start rooting around with wires, check all the fuses to make sure others aren't blown. Sounds simple, but my 91 Sonoma used to put the dome lights on and turn the radio off when the horn was pushed, which didn't go on. Ended up being a blown fuse on the accessory circuit, which still worked:eek1:. It took me forever to find and a lot of choice words...
     
  6. 86dieselburb

    86dieselburb 1/2 ton status

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    First thing I did was check all the fuses. Seems now it blows the fuse whenever the lights are turned on. I torn out a trailer braking device. Hoping that might be the problem, no go. I tore out the round trailer light hook-up seeing as how it was mickey moused, still no go. Did fix all the bad PO spliced in wiring at the rear. And put in a 4 prong flat connector that plugs directly into the harness.

    Next on my aggenda is to trace the wiring along the frame and if that dont find anthing, I tear the dash out. Need to replace the dim gauge light bulbs anyways, well that is if I get the problem corrected seeing as how the gauge lights are on the same fuse...lol Plus I can put in a new light switch that i've had sitting around from a previous project. After all that ifin I cant find it I give up...lol
     
  7. 86dieselburb

    86dieselburb 1/2 ton status

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    Replaced the headlight switch, no good there. I've checked the wiring that runs along the frame, well the parts that are not in that plastic sheathing. Seems fine. And the sheathing seems to be in decent shape and not looking like it has worn through anywhere. Cant get to the section by the gas tank. I need to pull the rear bumper for that. But I was thinking, couldn't I pop the brake/tail/blinker wiring at the bulkhead connector in the engine bay and put 12 volts to the taillight wire? Does the bulkhead connector come off in three pieces? That should tell me if it is the wiring going to the taillights or under the dash somewhere. Anybody have a schematic? Was wondering what color wiring is the taillight.
     
  8. zeroz400

    zeroz400 1/2 ton status

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    http://brochures.slosh.com/wiring/ Theres some wiring diagrams. You say you checked your wiring going to the back, were you using a test light to see if there was power going back? If not then your problem is before that. Get the wiring diagram and make a game plan, you need to isolate the problem.
     
  9. 86dieselburb

    86dieselburb 1/2 ton status

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    I love this place. Thank you for the link. Helps to know which wires do what.

    My idea was to pop the bulkhead connector for the taillights and put power to the wire that is for the taillights. Thats the only way I can think of to be absolutely sure that power is getting to the rear since the fuse keeps blowing. Now that I know which wire, I wont even have to pop the bulkhead connector. I can tee into it near the connector and apply power from the battery.

    After looking at the schematic, I have alot more places to look :doah: The marker lights are part of that circut also.

    Thanks again
     
  10. 86dieselburb

    86dieselburb 1/2 ton status

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    Success...turned out to be a wire comining from the alternator. The last place I would have thought to look. I just happened to drop something and when I reached for it, I noticed the wire connector was just touching the battery post. Oh well, atleast I cleaned up the PO's mickey mouse trailer light wiring.
     

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