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Old 10-06-2012, 02:56 PM   #1
99redimpreza
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Default Looking to hook up a rpm wire but dont i know know where to tap into to

I have a 99 impreza with no rpm gauge. I bought a rpm gauge and I don't know where to hook into. I tried every wire running into my ignition coil and still never worked.
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Old 10-08-2012, 01:38 AM   #2
Franko
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Old 10-08-2012, 09:03 AM   #3
99redimpreza
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It's a 2.2 not a 2.5 and there is a blue wire at the coil and it didn't work
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Old 10-08-2012, 01:50 PM   #4
GrundleJuice
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What kind of signal does the tach need? Is it an oem Subaru gauge or aftermarket? Some electronic digital techs can be picky about the signal being a square wave and reaching a certain voltage.
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Old 10-08-2012, 02:50 PM   #5
99redimpreza
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No it's a sunpro one. I'm not sure what kinda signal it takes. Here the picture for it it's the middle one.
https://www.google.ca/search?tbm=isc...20&bih=356#i=9
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Old 10-08-2012, 03:41 PM   #6
GrundleJuice
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The installation instructions should give you the info for what it needs for a signal. A picture of it doesn't give a useful info. Most ignition system manufacturers like MSD even make an induction pickup you can attach to a plug wire.
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Old 10-08-2012, 06:53 PM   #7
99redimpreza
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The instruction manual gave me a list of vehicles to look from and where to plug it into but Subaru isn't on there. I looked everywhere and tried the blue wire but nothing happened.
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Old 10-08-2012, 07:20 PM   #8
imma_stocker
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Have you contacted the manufacturer? That's step 1.
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Old 10-08-2012, 07:48 PM   #9
99redimpreza
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Yes I have. They said it should be in the manual and its not
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Old 10-08-2012, 08:32 PM   #10
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Quote:
Originally Posted by 99redimpreza View Post
Yes I have. They said it should be in the manual and its not
And, what kind of signal does it need? Sine or square?

Sunpro wires:
Red: +12 volts with the key in the "on" position
Black: Ground
Blue or White: Dash lights
Green: Tach signal from engine

Instructions
"Should you encounter unsatisfactory tachometer
operation (erratic, no reading, etc.) on engines
equipped with high performance and/or
aftermarket ignition systems or ignition coils, you
may have selected the incorrect tach connection
point for the tachometerís GREEN lead, or a
tachometer filter assembly may be required.
Contact the manufacturer of the ignition
system or ignition coil for information
regarding tachometer connection to his
product and/or the availability of an electrical
filter assembly if required."

Not all tachs work out of the box, they often require a converter to change the input signal into a form the tach can actually read.
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Old 10-08-2012, 09:09 PM   #11
99redimpreza
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I don't know what sign or square means. All I'm looking for is a wire
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Old 10-08-2012, 09:19 PM   #12
Uncle Scotty
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swapping the cluster would be FAR-FAR less problematic
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Old 10-08-2012, 09:59 PM   #13
imma_stocker
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Quote:
Originally Posted by 99redimpreza
I don't know what sign or square means. All I'm looking for is a wire
Sine and square wave are two different signal types. Both translate to a signal pulse, but if you wired everything right, and are testing it right, the ground wire from your ignition coil should tell the gauge what it needs. If you dont know the difference you didn't do your homework before purchasing a tach. Go check what's compatible with your car on summit or jegs.
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Old 10-08-2012, 10:32 PM   #14
99redimpreza
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I didn't know there was two different singles. All the gauge will do is do about half the cars rpm when I tap into the blue wire.
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Old 10-09-2012, 01:05 PM   #15
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Quote:
Originally Posted by 99redimpreza View Post
I didn't know there was two different singles. All the gauge will do is do about half the cars rpm when I tap into the blue wire.
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Old 10-09-2012, 03:28 PM   #16
GrundleJuice
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Quote:
Originally Posted by 99redimpreza
I didn't know there was two different singles. All the gauge will do is do about half the cars rpm when I tap into the blue wire.
If you have it set up for an 8 Cyl engine then facepalm is the least of what you need. Chk how to change for the # of cylinders. Might be a jumper wire or a pin you need to ground or unground or a tiny switch.
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Old 10-09-2012, 06:50 PM   #17
99redimpreza
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It's just a switch you can set it for 2 6 and 8 cylinder. I had it set for 4. I figured that much out
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Old 10-09-2012, 07:11 PM   #18
imma_stocker
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http://www.northursalia.com/modifica...ng/wiring.html



If you can't figure it out from information provided in this thread, you should not be messing with any wiring....

Actually, grab a fork and play with the outlet in your wall.
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Old 10-09-2012, 08:31 PM   #19
GrundleJuice
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There is always the possibility that the tach is faulty. Have another vehicle you can test it on?
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Old 10-09-2012, 08:56 PM   #20
99redimpreza
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All it does is when I plug it into the blue wire is read only about half the rpms
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Old 10-11-2012, 12:59 AM   #21
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Your aftermarket Tach probably doesn't match with the Subaru pulse pattern. The OE Tach reads 2 Pulses per rev. Perhaps your aftermarket Tach is configured for a different amount of Pulses per Rev and therefore reads wrong.

You will need a configurable Tach which allows adjustments so you can setup the amount of Pulses per Rev. If it can't be done you could always make your own electric circuit with a simple Timer (555 or similar) to make your own pulse generator depending on the Input signal to match the Tach.

First step with problems like this is to get out the oscilloscope!

Jasper.
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Old 10-11-2012, 12:07 PM   #22
99redimpreza
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I can take my tack back do they make a tack that will work with my car?
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