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Weird lighting problem

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by BillyBob, Jun 9, 2001.

  1. BillyBob

    BillyBob 1/2 ton status

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    Okay, this is REALLY weird. But I'll try to explain it the best that I can. I was sitting in my 84 last night, trying to take the dash apart. Now, I have this weird flashlight/compressor thing. Last time I tried to use the compressor with this truck's ashtray/lighter power source it didn't work. So I figure I give it another shot. Sure enough, the light works. Then I try the compressor, but if doesn't work. INSTEAD, the rear cap light, which I thought was dead, turns on. I turn the compressor on and off, ant the light turns on and off with it. So, while the light is on, I figure I should try the interior light switch. So I turn the switch, the rear light turns off, and the under dash interior light turns on. I try to turn it off, and it won't turn off! I had to take the bulb out! what the heck is going on??? I was thinking maybe it's a bad ground. If it was a fuse, it wouldn't be getting power at all. Now I have to figure out how the lighter and interior lights are all hooked together. All the other lights seem to work fine. This is PMO bigtime. Anyone got any ideas?

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  2. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    HAHAHAHAA that is totaly weird!
    Ok since the under dash light and the ashtray are right next together here is my theory. Some monkey brain got the wires crossed up. There was some short and he tried taging the cig for the positive. The dome light switch and dash switch work by going ground. When you plugged in the compressor it shorted out the cig plug and managed to complete the circuit to the rear light. The second thing to check is the rear dome plugs into the fuse box under the dash. It may be into the wrong slot. My wife managed to kick some plugs loose including the power windows in her truck (down of course and in rain and I was 60 miles away at Tellico). My bet is that happend in the past and it got in the wrong terminal. When you shorted out the cig plug my bet is there is a blown fuse in the box so it's backflowing the dome light power through the lights (the rear cap light) to find gound and complete the circuit.
    As I recall the light under the dash should have a orange and white wire as does the wire unning to the cap. If you pull back the capet some on the driverside you will see the cap harness comming up and trace it till it plugs in. My bet is if it's next to a fuse that fuse is also blown. Just need to move that plug over to Dome and it should work.
    Have you tried your horn? bet it's out also or it turns on the dome. SERIOUS I have seen it before. Hmmm as I recall on that one the dome light positive was tagged by a screw to ground. Blew a fuse in the box and power from the horn backflowed and got ground at the place where the screw hit the wire. Might pull up the door trim. Bet you find a short on the door trim or one of the screws that holds the side pannel next to the seat belt. Check that before moving any wires in the box.

    Diging it in the dirt with my K5's
    Grim-Reaper
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  3. BillyBob

    BillyBob 1/2 ton status

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    Sh*t dang, you're right. The horn don't work either. I figured that was a fuse thing. I didn't expect it to come to this though. Anyway, I'll check my fuses tomorrow. Anyone know where I can get a diagram of an 84 silverado fuse block? Chiltons NOR Haynes have a pic of the exact block. I don't wanna go searching mindlessly

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  4. Storm Trooper

    Storm Trooper 1/2 ton status GMOTM Winner

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    I think you should call a priest and have an EXERCISIM done!
    Sounds like grims got you covered but good luck........
    what a mess! I wish I could help you with the diagram but..... have you done a serch on the net?, I found things like that out there before.

    [​IMG]<font color=red>[/b]"Rid'in HigH in my K5"[​IMG]
    ....[​IMG]<font color=blue>[/b]"6" Lift -<font color=purple>38.5's"[​IMG]....
     
  5. Can Can

    Can Can Pusher Man Staff Member Super Moderator

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    Well, BillyBob, it looks like it's your lucky day!!!!!![​IMG] I'm in the process of sending you a scan of the fuse box diagram and fuse requirements straight from my 84 owner's manual.........let me know if it gives you the info you need.



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  6. Pugsley

    Pugsley 1/2 ton status

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    My suggestion would be to place a cross on the dashboard, then hire a priest! Seriously though, I'd bet that Grimmy hit the nail on the head.

    I'm so poor I can't even pay attention [​IMG]
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  7. Twiz

    Twiz 1/2 ton status

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    Yet another FYI

    Dome lights, Horn, And "cig" lighter, often share the same fuse, sometimes the "radio" fuse is thrown in for good measure, depending on the car or truck make and model. But in normal G.M. fashion, it is fairly consistant. They also share the same ground circut.

    So, Don't be surprized when something goofy happens when something goes a-miss. It is a designed in deal and simplifies assembly. Wireing diagrams help out ALOT! If you don't have one, hit the basics- Power in and power out. Poor or loose connections, Corroson, and "what did I screw with last".

    -Light bulbs have a odd tendency to "weld" the filliment back togather at just the right or wrong time (depending on how you look at it).
    -Cig lighter wireing on K5s get worked hard, That would be my first check.
    -Any wireing under the floor is prone to carroision.
    -Loose grounds can cause a few "gray hairs" to sprout
    -process of elimination

    Twiztid
     
  8. BillyBob

    BillyBob 1/2 ton status

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    Canmore- Thanks for the scan! It was exactly what I needed! I'm keeping the printout in the glove box just incase!
    Anyway, I finally have the interior lights under control since the fuse was blown. I got a new one, but the horn still doesn't work! Also, my blinkers and 4 ways are gone too.. I thought it was the directional fuse, but I tried it in my other truck, and it's fine. Man, this truck was supposed to be on the road this week too! I guess it's gonna have to wait till I get this electrical garbage outta the way. Anyone got suggestions on what else could be the problem? Better yet, anyone have a spare voltmeter they wanna give me [​IMG]. I'd go out and buy one, but the budget is WAY tight.

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  9. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Uhhh you just drop in a motor? You hook up the ground wire from the back of the passengerside head to firewall?
    All sorts of weird stuff happens when that's left off. Get all sorts of weird power back flows through wires. Tries to pull ground the lights and gages and turn signals don't work right.

    It's not my damn planet monkey boy!
    Grim-Reaper
     
  10. Flyinhi86

    Flyinhi86 Registered Member

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    Seems like the same problem I'm having. Boy auto electrical is a whole new world compared to normal residential, etc. I tackled it last year but put it away in winter. 35" mickey thompson baja claws in snow and -35 C is not a good combo. About to takle it again let me know how yours works out.
     

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