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As y'all know I am a Noobie.. So now that I have a tachometer voltage oil pressure and water temp gauge physically installed under the dash of the car, I need help powering the sucker. I never know what wire to tap into so it will turn on with the key in the ON Position..
So what wire to use?
Another question::: the gauge came with its own oil pressure sensor abd temp sensor. Well issue is that they are too small for fittings needed for my 302... Is there a converter / adapter I can use to make these fittings fit into the larger holes ?
Once I have that, I'll run seperate , new wires from these sensors to the gauge, so I don't have to mess with the wires behind my dash, and they can just stay disconnected and tie wrapped.
I tested the gauge out by connecting it straight to the battery, and giving it tach input from the negative side of my cool and yes it does work.
This gauge is not a beauty in any way as far as the classic look is concerned .. But it's electronic and not 400 bucks lol. It's something that works .. when I have more dough, I can do custom beautiful gauges
So please guide me
Thanks
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Not that it matters but this is it ::
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To the bolt on the center of the key switch would work for the + 12 volts. I would use an in line fuse if one is not installed.
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would it be a good idea to use the fuse box for power supply?
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Gaba wrote:
would it be a good idea to use the fuse box for power supply?
I used the same power supply that I ran for my radio head unit. Pretty sure I split it off from the ignition and fused it.
You can get brass fittings for your stock oil sending unit that will accept the pressure sensor tube fitting. They're fairly common.
And if they're functional I say go with it. I bought a cheapo triple cluster for like $25 like six years ago. I now have a nicer Jegs set sitting in a cabinet in my garage that I keep wanting to put in, but the cheap one works so darn well that I can't justify the time spent to replace it!
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Folks I have run into the WIERDEST problem I have ever experienced ..
I found the power supply to hook the TACH to.. temporarily.. in the fuse box, on a fuse for accessory that turns on with the switch..
Ok... So , i connect the tach up, and start the car, and the tach goes to 2000 and sticks there.. and then as I would give gas to the car, it would just keep rising.. until it would max out, and my engine is actually ideling. .. Its Like its got an issue somehow. ok .. Starting to troubleshoot the best I know.:
1) Use the positive instead of the negative on the coil to see if it makes a difference : NO
2) Disconnect everything take the tach to the engine bay, go straight to the battery red to red black to black and green to the positive terminal of the coil (just to check)--- NO
3) Use the negative of the coil : Woalla!! Tach is on and following rpm like its supposed to. everything looks good.
4) Now that is interesting.. what was wrong inside the cabin.. Ok.. may be becuase my TACH input is running to my remote security and remote start box, may be tach doesnt like the current drop because of the splice... Lets take another wire and run it straight from the coil to inside the cabin and try :::::::::::::::::::::::::: NO!!!!!! same freaking tach rising higher and higher slowly till it maxes and stayes there..
5) OK BAD GROUND: MAY be he body isnt grounded well enough , so run another long wire from the battery's negative terminal all the way to inside the cabin.. cant get a better ground than from the battery itself.. NOPE! @__@ !! Why does this hate me? LOL
------So the only thing left to do that I might try is to power the sucker from the battery straight and use the spliced signal wire I have inside the cabin to read the tach readings.
QUESTION: Why is this happening. Why does the tach works straight off the battery in the engine compartment.. but CONSISTENTLY does not in the cabin.. I am a little frustrated. Its a Tach for crying out loud! how hard can it be? ? ? ??
By the way I found the NPT adapters for the oil and temp electronic sensors at NAPA.. but only will it work after the stupid tach decides to freaking work!!!!!
I am an electrical engineer.. and a tach is defeating me.. HELP!
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I've never tried it, but I've always heard that if you hook up the tach signal wire (usually green) to the positive side of the coil rather than the negative side of the coil it would make the tach behave like a volt meter... which kinda sounds like what yours is doing.
Be sure your tach signal wire is hooked up to the negative side of the coil.
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I am positive that it is on the negative terminal :D
why i say this is because, I double triple checked.. I am running petronix points and a flmae thrower coil.. hope that doenst make a difference..
Like you said it wont work or wont work right on the positive, that is true as even in the engine bay it didnt work.. but in the cabin is where its powered off a port on the fuse box.. (even if grounded) straight to battery, it doenst work.. or it "acts like a voltmeter"
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Sorry... I wasn't trying to insult your intelligence... just making sure.
The pertonix shouldn't matter...I am running a pertronix II and flamethrower II coil and my tach works fine.
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Michael H. wrote:
Sorry... I wasn't trying to insult your intelligence... just making sure.
The pertonix shouldn't matter...I am running a pertronix II and flamethrower II coil and my tach works fine.
ohh not at all... Its a good point.. and yes small things can be missed..
amkes me want to install a new fuse block in there getting power straight from the battery with a relay activating power to it.. Anything you know thats a fuse box with a built in relay like that? I am just asking becasue it will be prettier .. to install with a relay already in there, rather than having a relay installed seperately somewhere. Please let me know.
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Maybe try disconnecting the remote start and security from the tach. Verify you have 12 volts at the tach P.S. input.
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how i know that its 12 volts is that this tach has a voltage meter in it.. Its tell me what its getting (one of the 4in1 things) .. So that would be somewhere from 12.1-12.8 when car is off.. ranging up to 14.1 with the car on (on alternator) ..
I did actually, if you notice, run a seperate wire from coil to the tach to make sure that the remote start was in no way interferring with the TACH.. no bueno
and i notice you said to disconnet it completely from tach.. that was an interation I did too.. I removed the remote start TACH signal and left just the new wire on the coil, accidentally actually.. and that gave no good results either.
But in the engine bay with this tach.. the coil had the remote start wire hooked on to it, and the tach was working with it on.. CONFUSION CONFUSION lol
Last edited by Gaba (3/13/2014 11:06 AM)
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Try your tach's red wire, which should be for switched 12v, directly on the stud on the back of the ign switch. This is where mine was hooked up and worked well. As mentioned, the green should go to the neg side of the coil and black to ground.
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I'll try to get to that.. with the underdash AC , its a bit crowded up in there. and I dont like to pull on things, as you never know what old wiring will fall apart.. any way of getting to it from the front..
again remember NOOBIE here :D
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The next thing i would try is pull the wire you ran from the engine bay to the car cabin (Battery + , Battery - and Coil - ) pull them back out into the engine bay and use the same wires and try it again under the hood. You may see something you missed.
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No way to get to it from the front, unless you pull the switch which is more trouble than it's worth. You can probably do it all by feel. Reach up to behind the switch and feel for the stud. I forgot the thread size but if you have a eyelet on the end of the red wire you might be able to get it on the stud and tighten with a suitable nut.
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wsinsle wrote:
The next thing i would try is pull the wire you ran from the engine bay to the car cabin (Battery + , Battery - and Coil - ) pull them back out into the engine bay and use the same wires and try it again under the hood. You may see something you missed.
I haven't done red power wire from the engine bat to cabin yet. I might try that. It that doesn't work, I'll have a priest throw holy water at it lol
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Sounds like a hostile tachover to me...
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If holy water doesn't work I guarantee a 3 pound hammer will.
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wsinsle wrote:
If holy water doesn't work I guarantee a 3 pound hammer will.
lmao... !! good to know.. I just bought one too!! hahahahahhah will "break it in " :D
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to all that helped. went wit hthe mechanical style gauges.. mounted under the under dash.. Tach is on its way and will be mounted on the side of the steering column. soon ..
but .. atleast wanted to update whats going on
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