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Weak tail lights

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Goose, Aug 28, 2006.

  1. Goose

    Goose 1/2 ton status

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    My new '86 has some lighting probs.
    The turn signals to the rear are really weak, they just barely light up.
    The brake lights don't work either.

    Funny thing is if I have my left turn signal on and step on the brake the signal stops blinking!

    I have fixed some of the old splices where the PO used the clamp on slice thingys that always corrode. I've also checked the wiring around the steering column. I dropped it down and looked for frayed or broken wires.

    I'm obviously getting some wires crossed between the brake and left turn signal. Anywhere else I could check?? Anybody with a similar prob???

    thanks in advance
     
  2. k20

    k20 3/4 ton status

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    didnt notice if the 86 is a truck or not, but I had problems on mine w/ the lights after I had a line-x liner sprayed in. Screwed up the grounding of the bed to the frame, run a groundstrap from the bed to the frame, they work like a charm again.
     
  3. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    Might wanna take a peek at the main wiring running along the frame.. iirc, it's a green, yellow, white and brown bundle... They like to chafe thru where they use slide-on clips to hold it to the frame... check your grounds in the light buckets in the back too....
     
  4. Goose

    Goose 1/2 ton status

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    The PO added some ground to the frame from the bed. Sounds like he had the same problem. I'll double check his work and check for chaffing.

    One area I couldn't check was above the driver side fuel tank.
    I'm in the process of removing the tank shield and tank.
    What a mess! Mud is packed around the tank, and I smell fuel.
    I'm prolly gonna have a leaky tank.

    Fun, fun, fun
    anyway, thanks for the advice
     
  5. Goose

    Goose 1/2 ton status

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    Update:
    Got the driver side tank shield off. It was holding about 40 pounds of mud, sand, and straw against the tank. It would make some real nice adobe.
    Anyway, found a dent in the front of the tank and a good deal of surface rust on it. Still smelled like gas, so I think I know what that means.

    Now I need to drain it and drop it so I can access the wiring above it.
    Anybody want to help getting covered in mud and gasoline????
     
  6. sponsoredbydad

    sponsoredbydad Dune Slaying Sand Junkie Premium Member GMOTM Winner

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    Wireing takes pacitence to trouble shoot so just start at one end and move in one direction [dont' jump all over]. One problem I had with a truck was the trailer wireing the PO had no idea what they were doing and that had the results you are describing. It's something easy to check out anyway.


    chris
     
  7. sponsoredbydad

    sponsoredbydad Dune Slaying Sand Junkie Premium Member GMOTM Winner

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    O-yea I know this sounds stupid but I've seen people put the bulbs in backwards. the 1157 bulb that runs both brakes/tail/turn siginal have offset nipples that if forced will go in and run the lights dimmley and when you turn on the siginal you can't see the brake. Or the tail lights look as bright as brake lights. Like I said this sounds stupid but I've seen it.

    chris
     
  8. Goose

    Goose 1/2 ton status

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    Update

    Maybe I have been jumping around a little....
    anyway I replaced all the fuses with the correct amp and then checked the lights tonight in the dark. Thought this would help since what does work has been dim.

    BIG PROBLEMS!

    First I turned on the parking lights, key in OFF.
    The left turn signal in the dash lit up dim.
    Parking lights to the front came on, but not to rear.

    Key still in OFF, left turn signal:
    "CHOKE" light blinks!!!!

    Key ON parking lights on:
    still no rear parking lights

    Key ON, left turn signal:
    parking lights blink!

    Key ON, right turn signal:
    parking lights blink

    Key on, turn signal, plus brake
    everything stops blinking.

    This is soooo mesed up I'm starting to think
    head light switch has internal short in it.

    Anybody else?????

    thanks
     
  9. BowtieBlazer

    BowtieBlazer 1/2 ton status

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    sounds like the printed circuit has a bad ground or short hence the different incorrect blinking lights
    could also be the turn signal switch playing games with the key off no turn signal anything should work

    Start at the fuse block and trace the wires back to the back like you are doing, if he had really bad butt connecter or taped wire splices for long enough some of the wiring may be corroded and ruined. I'm talking replacing as little as 2"-6" of wiring as much as the entire length depending on the moisture exposure. Or if you like check from the brake lights forward. Make sure each tail light bucket has a ground in the wiring near by and that the light sockets aren't melted when the connecters contact, probably wouldn't hurt to spray a little contact or electrical parts cleaner and use a little dielectric grease when reinstalling.

    Make sure you also have the following ground straps... motor to frame, frame to body around the firewall, radiator support and tailgate. battery to frame and body.
     
  10. k20

    k20 3/4 ton status

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    Id place money on a grounding problem. Thats close to what mine was doing when the ground was bad, cept mine, with the turn signal on and hitting the brakes, I got police style wig-wags....to bad I couldnt keep just that feature lol.
     
  11. Goose

    Goose 1/2 ton status

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    Update

    You guys nailed it! Ground problem on the rear.

    The grounding wires the PO installed were not tied into the wiring harness by the tail lights, and therefore did not do too much.

    I redid the grounds at the rear and also the ground from the engine to fire wall.

    The brake and turn signals work now, but no parking lights or dash lights.

    After lunch I get to dive into that probelm.

    On a related note, the driver tank was all rusted out in the front. About a 12" by 12" area stays wet with fuel. Luckily, my brother has a spare tank.

    thanks for the help
     
  12. k20

    k20 3/4 ton status

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    No parking lights or dash lights....are we just talkin side markers, or are you talking no parking lights at all, front rear side? Could be the headlight switch. Maybe a loose plug on it, IIRC there are 2 or 3 different plugs on the back of it, dont really know what they do, maybe one came off?
     
  13. Goose

    Goose 1/2 ton status

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    No dash, side marker, or front or rear parking lights.
    I replaced the fuse and it blew again in about 1 second.

    I spent about an hour looking for where the hot wire could be getting grounded out, but could not find any.

    I checked the fuse location with my multimeter with the fuse removed.
    With the switch on...
    The right half is hot (12.4v) and the left half is grounded.
    With the switch is off...
    Neith side shows powered or grounded.

    This leads me to believe the switch is good and the problem is somewhere in the wiring at or past the firewall.

    This make sense to anybody??
    The problem now is I cannot find any problems.

    Could the problem be around the gage cluster?
    I really need to study a wiring diagram, but I so much like looking at it in person.

    thanks again
     
  14. BowtieBlazer

    BowtieBlazer 1/2 ton status

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    thats reading correctly...the fuse gives power to the left half


    Is the fuse blowing with just regular running lights on?

    If its not the only difference is the head lights being on which would lead me to the head light switch.....however thats not definate, no dash lights and no tail lights its a direct corrolation that tells you something isn't right if the dash lights aint on
     
  15. BowtieBlazer

    BowtieBlazer 1/2 ton status

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    Check this and tell me if it works or not and i'll give you my across the internet diagnosis

    truck ignition ON but not running does right and left turn signals work? Front and rear?

    can you turn on your head lights without blowing a fuse? If it blows what about with the ignition OFF can you turn on your headlights, what about parking light mode?

    if all that works when you turn on a turn signal does it blow? if not is it when you hit the brakes?

    Oh yeah what year model vehicle and fuse number is blowing?
     
  16. Goose

    Goose 1/2 ton status

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    Okay...
    Key On, truck not running all turn signals work.

    Fuse blows when head light switch pulled out to first notch for parking light mode. Headlights work when pulled out to second notch.

    Brakes/turn signals do not blow the fuse.

    It's a '86 K30, the fuse is the "T/L CTSY", 20A

    I've been distracted by learning my other gas tank leaks.....ALOT.
    Found one for $45, plus my brother has one when he makes in from out of state.

    anyway, I'm getting closer and the projects are multiplying
    thanks.
     
    Last edited: Sep 1, 2006
  17. BowtieBlazer

    BowtieBlazer 1/2 ton status

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    I'll have to double check mine but thats more than likely in the headlight switch if it does in position 1 but not 2 if you can reliably drive around in position 2 with functioning brake and turn signals and dash lights its definately in the switch
     

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