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Stock Oil Pressure Gauge Help-- ATTN JarheadK5

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Todd78/87, Apr 24, 2000.

  1. Todd78/87

    Todd78/87 1/2 ton status

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    When I turn my key to ON, the needle on my gauge resets to zero like it's suppose to, but when I start the blazer, the needle pegs out to the right past the 60 mark. Like 3 o'clook on the dial. A friend of mine has a truck that did the exact same thing. He changed the sending unit and the gauge and it still did it. He also took the printed circuit off the back and inspected and cleaned it up. I have a new motor in mine with a new sending unit. I talked to a dude at Chevy and the first thing he said was "sending unit" before I could finish,, I told him I have a new one... he said maybe it's an 80 psi sending unit, not a 60. He said it might be stamped on it, but I cant see any numbers on it from what little I can see of it. Really don't want to pull it out. But if that was the case, wouldn't it just be 20 psi off?
    Anyway, I have my dash most of the way off, so I decided to take it all the way out and test some voltages out.
    I traced the paths on the circuit board to the pins of the harness and took measurements. The gauge has three prongs. With key ON, I get 12.xx volts on one peg and nothing on the other. ( One is ground) When I start it. I get nothing on the one that had 12 and 14 volts on the one that had nothing before.
    I grabbed a hot and ground wire out of the dash and held them to the back of the gauge. On the 12 volt side.. the gauge Zero's like it's suppose to. When I touch the 12v wire to the other post,, it pegs out to the right.
    Now,,, when I put it all back together, I did the same test with the harness plugged into the circuit board and the gauge in the dash. With the truck running I get 4.xx volts on the original 12v "On" peg. and neg 10v on the one that showed 14v's. There are no resistors on the circuit. But it doesn't seem like that matters, cuz the gauge does the same thing either way, with both sets of voltages. I'm not opposed to putting in an aftermarket gauge, just don't want to if I can fix this by cleaning a contact or replacing a wire or whatever. Anyone figure this one out?
    Does anyone have a working stock gauge who is in the posistion to take some voltage measurements for me?

    Thanks

    Todd 78/87[​IMG]
    [​IMG]
    Alaska Bound
     
  2. jarheadk5

    jarheadk5 1/2 ton status

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    Re: Stock Oil Pressure Gauge Help

    Sounds like there's wires crossed up somewhere in the circuit. The wire that you think is a ground seems to be getting power from somewhere. If you (or someone out there) has a complete wiring diagram, you should be able to trace the circuits and see if something's connected wrong, shorted, rubbed thru, or ???. Personally, I'd save myself the hassle of figuring this out and go with an aftermarket gauge. I think the factory gauges are unreliable anyway.

    Just my 2 cents...Hope it helps you. Good luck!

    [​IMG] Semper Maintenance!
    [​IMG] So many ideas, so little money...
     
  3. Todd78/87

    Todd78/87 1/2 ton status

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    Re: Stock Oil Pressure Gauge Help

    Yeah,,, I know. I just was hoping that someone was in a restore stage and had quick access. A couple voltage measuments on a working system would tell me a lot.

    Todd 78/87[​IMG]
    [​IMG]
    Alaska Bound
     
  4. jarheadk5

    jarheadk5 1/2 ton status

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    Re: Stock Oil Pressure Gauge Help

    Wish I could help more...In 3-4 weeks I'd probably be able to get readings when I install my Autometers, but I'm sure you don't want to wait that long.

    [​IMG] Semper Maintenance!
    [​IMG] So many ideas, so little money...
     
  5. Todd78/87

    Todd78/87 1/2 ton status

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    Re: Stock Oil Pressure Gauge Help

    Are you putting new ones in the stock location? If so, what size are you getting? I didn't know how they would fit with those metal clips sticking out of the board. Do you have to take those off? Or is it deep enough the way it is?
    Or, are you going to find all this out when you do it? [​IMG] If you don't know, I'll go get one and find out and let you know.

    Todd 78/87[​IMG]
    [​IMG]
    Alaska Bound
     
  6. jarheadk5

    jarheadk5 1/2 ton status

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    Re: Stock Oil Pressure Gauge Help

    Sorry it took so long to respond. Been working and flying a lot lately.

    Uhh......metal clips?? Board?? I guess maybe I should have taken a look behind the dash!! Can you say DOH!!? (Picture the "Simpsons" episode when Homer's in NYC and the cop writes him another ticket...) Oh well, I guess I'll find a way to have my gauges. Maybe a windshield pillar pod like the riceburners do?

    Boy, this really shoots a hole in my plans for a cool dash...

    [​IMG] Semper Maintenance!
    [​IMG] So many ideas, so little money...
     
  7. Todd78/87

    Todd78/87 1/2 ton status

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    Re: Stock Oil Pressure Gauge Help

    No problem, Man,,, I thought I "heard" someone say they put an aftermarket gauge in the stock location. I ordered a 2 1/16" mech gauge, should be here Mon. I'll see how it goes and let you know.
    Yeah,, the stock gauges "plug in". They have metal posts on the back and they "plug in" to metal clips. And there is only one big plug of wires that go to the back,,, all the gauges are controled via a flemsy plastic sheet with copper "paths" stuck to it that run from where the wire harnes plugs in, to the various gauges. Anyway,, I'm gonna try it.
    I'll let you know.......

    Todd 78/87[​IMG]
    [​IMG]
    Alaska Bound
     
  8. Todd78/87

    Todd78/87 1/2 ton status

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    Re: Stock Oil Pressure Gauge Help - ATTN JarheadK5

    Hey Jarhead,
    I put my new oil gauge in today. I messed up big time. The 2 1/16th" gauge will go in the stock location IF you cut a hole in the clear gauge cover and trim the metal plate hole behind it. Well,, I was cutting out the clear cover and busted it all to hell, heheheh [​IMG] So, I figured if and when I get another clear cover, I don't want to take the chance of trying to cut that one also,, so I mounted it in the bottom left of the outside dash cover. I don't have air conditioning and never did, so there is no vent in the bottom left of the dash cover. So, I just stuck it there. Either be VERY carefull cutting out your clear lense,, or if you don't have air and are putting two gauges in, I would put them in the upper "cubby hole",,, I don't think two gauges would fit where I put mine.
    Anyway,, have fun man and let me know what you decide to do,, just for the hell of it. [​IMG]

    Todd 78/87[​IMG]
    [​IMG]
    Alaska Bound
     
  9. jarheadk5

    jarheadk5 1/2 ton status

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    Re: Stock Oil Pressure Gauge Help - ATTN JarheadK5

    Hey, thanks for the update. I now know a little better what you're talking about, because my outer dash cover (bezel?? the silver plate) is off too! My radio died, and to get it out I ended up having to take the plate off, among other things. Now I can see and visualize what I want to do. My plan is to cut the entire left side of the clear lens off, make room behind it as needed, and install 4 Autometer 2 5/8" gauges in the bezel plate, like the way a NASCAR dash looks (surface mount??). I have air, so the vents aren't really an option for me. If it works out, I'll try to get a pic or two posted for you and everyone else. If it doesn't...well, I'll come on here and beg for help and sympathy!! LOL... Anyway, thanks for the update, I really appreciate it!

    [​IMG] Semper Maintenance!
    [​IMG] So many ideas, so little money...
     
  10. mudfanatic

    mudfanatic 1/2 ton status

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    I think that your problem is the dash voltage regulator, it hangs behind the dash on 4 or 5 big wires it looks like a plug end and it is black, it just hangs there behind the oil /temp gages. This is a wrecking yard item only unless Year One has it.
    HTH
    Dan

    <font color=red>mudfanatic</font color=red>[​IMG]
     
  11. coopertwpk

    coopertwpk 1/2 ton status

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    a buddy of mine has the circuit board cut away on the left side and just left the gas and speedo hooked up
     

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