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stock dash questions*UPDATED*#2

Discussion in 'The Garage' started by big d, Sep 18, 2002.

  1. big d

    big d 1/2 ton status

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    anybody know what the white lite bulb plug in in the top right hand corner in behind the FUEL GUAGE is for ? it has a cable lead in and is a beeoch to take out. also, why is that gm made 85 mph speedo's in some years and 100 mph speedo's in other years. so far ive only found 100 mph speedo with the "blue highlite colors". all 85 mph speedo's i have found have the "orange high lite colors(with 55 in orange)". any body have an orange 100mph speedo? if so do ya want to unload it ? pm me. /forums/images/icons/grin.gif btw, it cant have the electric hook up on the back, or do you have to use this in a model that didnt have it ? will a earlier model's speedo cable hook up to a newer model's guage ? anybody know ? ok, heres some more info. if you pull the dash out and flip it over, all lite bulbs are held in by little black sockets x-cept two-one is the 4x4 indicator lite under the speedo and the lite i am talking about behind the fuel gauge. im thinking this MUST be some sort of sensor. it is a heavier duty socket than the rest and has a metal prong protruding from it that these wires hook to. does this help ? any one ? this should peak some one's curiousity ! /forums/images/icons/tongue.gif /forums/images/icons/grin.gif /forums/images/icons/confused.gif
     
  2. uglychevyZZ4

    uglychevyZZ4 3/4 ton status

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    Re: stock dash questions

    no, older wont work with alot of newer ones, and yes mine has the bulb just behind the speedo, one is for the speedo light and the other is for the highbeam. mines a 77' if we had a year we might be able to help better. /forums/images/icons/wink.gif
     
  3. tori89k5

    tori89k5 1/2 ton status

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    Re: stock dash questions

    I think the cable thing is actually a fiber optic that runs to the ash tray so you have lite there, least thats how it is on my '90
    As far as the 85 mph rating on the speedo... i think it was a gov. law type thing. I think you'll find most american cars in the mid 80's that were this way.
     
  4. big d

    big d 1/2 ton status

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    Re: stock dash questions

    actually i was wrong, that lite and wire is in behind and at the top behind the FUEL GUAGE . sorry, still have any idea ?
     
  5. big d

    big d 1/2 ton status

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    Re: stock dash questions

    hey, actually i was wrong, that lite/wire was at the top corner in behind the FUEL GUAGE. sorry, still have any idea what it is ?
     
  6. big d

    big d 1/2 ton status

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    Re: stock dash questions*UPDATED*

    TTT
     
  7. uglychevyZZ4

    uglychevyZZ4 3/4 ton status

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    Re: stock dash questions*UPDATED*

    how about it is just that, a wire to the light... /forums/images/icons/laugh.gif
     
  8. Michael

    Michael 1/2 ton status

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    Re: stock dash questions*UPDATED*

    My '74 had a small fiberoptic cable that went down to the wiper switch to provide light for it.
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: stock dash questions*UPDATED*

    Ok the fiber optic cable is for the ash tray in at least '81-ups, if not earlier. Dunno why they wasted time and money on that in a truck.

    As to the 85MPH, that was federal regulation, you'll notice no GM's (and since it was federal, every other make) until '86 or '87 got 85MPH gauges. (started probably about 1974) Stupid idea that people would slow down if their gauge only went to 85. Why not just make it 70 max then?
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    Speedo cable. Difference is screw on, or clip on. Later ones (at least '81-up until electric) were all clip on style speedo cables. Easier to swap cables than make it work on a different speedo if you have the screw on type.
     
  11. big d

    big d 1/2 ton status

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    nope this isnt the speedo cable. i know what one that is. i have found this not only in my rig (which is a 79') but in dashes up until at least the early 80's pre-tbi. ive had the pleasure of taking a part several dashes and they have all had this (when people cut the wires instead of taking out socket).ive followed the wires alittle and they head towards the passengers side in behind the blower control panel. sure wish i could find out what this was for or even it is important. thanks for responding.
     
  12. kennyw

    kennyw N9PHW Premium Member

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    Could it be for a dual tank vehicle? Maybe run to the tank switch on the pickups?
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

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    Ok you got that my two posts were for two different things? The white light bulb socket (or green in some years IIRC)on the back upper passenger side of the gauge cluster (as installed in the vehicle) is the fiber optic feed for either the cigarette lighter, or partially, the heater controls. (thanks to someone for making me doubt myself lol)

    The heater control head already has one lightbulb in at least the '81 up heater control head, so I doubt they would run aux. lighting to it. I'm still sticking with its for the cigarette lighter, and IIRC, it actually lights up the ashtray. Look at an '81-up truck around the ashtray/cigarette lighter area, (what would be the area behind the dash obviously) and look for the little "port" the end of the fiber optic plugs into. The end of the fiber optic line is actually brass as I recall, and is a press fit into an angled plastic fitting that sits in the metal somwehere around the ashtray.

    You can pull the dumb thing off, or swap the bulb housing, and do away with it. It is nothing but a light source for something else, that isn't important.
     
  14. big d

    big d 1/2 ton status

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    dorian,
    ok you where right ! that wire runs to the cig/ashtray compartment. now what exactly does it do and how do you check to make sure it is working. i want all stuff on my rig to work ! btw, you are the man ! /forums/images/icons/grin.gif
     
  15. dyeager535

    dyeager535 1 ton status Premium Member

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    Well, being fiber optic, it transmits light from that build (when the gauge lights are on obviously) to whatever it plugs in to. Probably to illuminate the ashtray a little bit.

    Can't argue with you for wanting everything to work right, even if I can't see why GM bothered to run that thing. /forums/images/icons/wink.gif
     

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