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Tach wiring.. a shot in the dark

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by wrathORC, Aug 10, 2002.

  1. wrathORC

    wrathORC 1/2 ton status

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    I have a tachometer out of a Monte Carlo (still inside of its cluster). It looks identical to the ones found in the 73-87 generation pickups/K5s.

    Does anyone know off the top of their head what terminal is which (ground, power, distributor) on a 73-87 tach? Do they even need power?

    I can sit there and painstakingly trace pathes on the cluster but that's what's been preventing me from doing it for the last six months.

    Also, does anyone happen to know which wire goes to the temperature gauge? This isn't a big deal because I can forage through my manual to find this one.


    Thanks
    -Brian
     
  2. dremu

    dremu Officious Thread Derailer Premium Member

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    Yap, they need power.

    I cheated and x-planted the circuit board when I installed my tach dash, so I don't recall off the top of my head which is which. There are three -- and thankfully only three -- connections, for ignition power, distributor, and ground.
     
  3. dyeager535

    dyeager535 1 ton status Premium Member

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    All the tach dashes for the trucks I've seen (no '81-ups though) have a seperate three wire tach harness. Thats what I'd do for the Monte one as well.

    Monte's I'd guess used the fuse panel connector for the power/ground/dist wiring, I'd find a late 70's camaro, take the tach/harness out of it, and use its wiring/plug to adapt to the truck.

    I really doubt the Monte one will "bolt in" the mounting tabs are bound to be totally different.
     
  4. wrathORC

    wrathORC 1/2 ton status

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    There are no Camaros or other musclecars in the junkyards around here. Well, that's not entirely true. There are no F-bodies, 'stangs, or other high performance vehicles in the junkyards that haven't been stripped of anything that might be useful.

    Nah, you're right, the Monte Carlo's tach won't fit without modification. I've got a couple spare 73-87 clusters and I was going to butcher one with the dremel tool to make it fit. The idiot lights are in the way (the ones that normally peek through the fuel gauge).

    I don't like column/dash mounted tachometers and no one makes a pillar pod for these vehicles. That means I'd have to buy a cluster off eBay (because all good clusters like that have been yanked out of the junkyards by now) with a tachometer and chances are it won't work.

    Thanks for the idea though.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    big, but http://yeagerd.home.mindspring.com/frankentruckpics/MVC-001X.JPG shows what a late 70's early 80's camaro tach face (and circuitry) look like siliconed to the stock truck fuel gauge. (so you can bolt it directly in) The Camaro fuel gauge face nicely fits over the stock truck face with silicone as well : ) It also happens to match the '81 up truck lettering. (although earlier Camaro lettering would likely match earlier truck gauges)

    You can find these on Ebay once in awhile, so you might keep your eyes open...should be a heck of a lot cheaper than the '81 up truck tachs!
     
  6. wrathORC

    wrathORC 1/2 ton status

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    excuse my language, but that's [censored] ingenious. i wonder why i didn't think of that. i believe the cluster is out of a monte carlo but i'm not sure. i found it foraging through my dad's junk and he's had over fifty cars as long as i've been old enough to remember them so who knows what it came off.

    the tach has six terminals on it. three of them don't look used (mounting purposes only). the other three are orientated for a plug. one says ground on the board but the other two are unintelligible.

    you got me so excited i went out and got the cluster for a picture. it's a little shoddy because i have a cheap camera that doesn't like taking pictures without natural light.

    [​IMG]

    i'd take a picture of the backside but it's kind of pointless since i took the terminals off the last time i had the cluster apart. i put the tach back in the cluster for the 500 mile trip here.

    anyway, it's a small cylinder (1" diameter maybe?) on the backside with a board about 2" square if i remember correctly.

    other than wiring the tach, this just got a lot easier. all i've got to do is cut a hole in the face of the tach so the idiot lights can shine through, remove the fuel gauge but leave its face, glue it in, use the fuel gauge out of the monte's cluster, stick it in the cluster out of one of my other trucks, steal my speedo, and use the plastic out of the other truck because it doesn't have the hole for the "quartz analog clock" like mine does. damn, it's a no-brainer now. the only thing is that the needles out of the other trucks are all a different orange and i lost one to the speedo from the monte.

    wiring the fuel gauge is a no brainer because i already butchered it when i added a second tank to my truck.


    thanks, now i wonder why i didn't think of that..
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    http://coloradok5.com/forums/showflat.php?Cat=&Board=blazer4x4&Number=124857&page=&view=&sb=&o=&vc=1

    http://coloradok5.com/forums/showthreaded.php?Cat=&Board=blazer4x4&Number=314602&Search=true&Forum=blazer4x4&Words=camaro%20tach&Match=Entire%20Phrase&Searchpage=0&Limit=100&Old=3months&Main=314203

    Are two of my previous posts.

    I *know* I used the same tach/fuel gauge face out of one Camaro, I was able to pic up another pair as spares : )

    In looking at my factory truck tach dashes (earlier than '81) it appears that I could fairly easily mount the plug for the older truck tach wiring on the Camaro setup. GM seemed to be real standard when using a seperate tach harness..2 prongs side by side, one by itself. Might not work just because the plug may be integral with the tach circuit board, but if not, easy. Not worth hacking up a factory tach though I guess, even though this is a "commercial" chassis tach dash.

    If you want, I can check the Camaro tach for correct terminals for ground, power and dist. lead. (late tomorrow)
     
  8. wrathORC

    wrathORC 1/2 ton status

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    I'm really sleepy but I'll give this a try.

    The Monte tach has three bolted-on prongs. I don't remember if they were all in one direction or two in one direction and another 90° but they were in the orientation of a sealed-beam high beam headlight.

    I can't remember what things look like on my other ICs but I had planned on soldering ends on some wires and bolted them on to the tach. I don't plan on soldering on the plastic circuit board.

    It's not in a real rush for you to find out what lead is which but if it's a five minute job then it'd be mighty nice of you.


    thanks

    i still can't believe i never thought of cutting the old fuel gauge.. something so simple and blatant.
     
  9. wrathORC

    wrathORC 1/2 ton status

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    I figured out how to wire it. However, due to unforseen problems I'm not going to use it. I was going to butcher my late seventies clusters but both the cluster itself is different and the plastic circuit board is different. Both of them have mechanical oil pressure gauges. Both of them have the speedometers mounted differently. This means excessive amounts of time butchering with the dremel tool and some quality time rewiring.

    Perhaps someday when I'm at a junkyard again I'll find another 81-87 cluster with cruise control (there's a weird shape for the electronic speed control sensor or something).

    I do, however, have a fuel gauge face with a tach siliconed on it.


    Nothing has gone right today.. While finally finishing up my remodeled bathroom I broke the toilet..


    PS: thanks for your help
     

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