Tach Signal Wire?
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Joined: Mar 2005
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Tach Signal Wire?
I'm installing a new aftermarket tach to replace the stock one (long story, I'll post a writeup of the mods when I'm done). My repair manual doesn't list which wire under the dash is the tach signal wire versus the power and ground wires - thankfully the lights are obvious.
The car is a 1975 with HEI ignition.
So my question is: assuming the wiring is stock, does anyone know which color wire is the tach signal, which is the ground, and which is the power?
And just for kicks, here's an interesting bit of wiring creativity I found while cleaning up some of the wiring. They're wires that go to the light bulbs that plug in behind the tach and speedo (there's also a green one with a light and a blue one with a light) - no idea where the red wire finally ends up.
The car is a 1975 with HEI ignition.
So my question is: assuming the wiring is stock, does anyone know which color wire is the tach signal, which is the ground, and which is the power?
And just for kicks, here's an interesting bit of wiring creativity I found while cleaning up some of the wiring. They're wires that go to the light bulbs that plug in behind the tach and speedo (there's also a green one with a light and a blue one with a light) - no idea where the red wire finally ends up.
Le Mans Master
Joined: Oct 2006
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From: Gladstone MO
C3 of Year Finalist (appearance mods) 2019
Take a look at the HEI disty cap. The one marked "TACH" the color wire that's plugged in there will be the one you're looking for. GM may be lots of things, but they were very consistent in their wires.
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Joined: Dec 2005
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If i remember correctly it is white w/blk stripe. that is whats in my 80 and fromwhat i rem from helping a buddy with a 76 it was white/blk also.
hope it helps and good luck - looks like "bubba" was crawling under your dash.
hope it helps and good luck - looks like "bubba" was crawling under your dash.
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Joined: Mar 2005
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Very cool, thanks for the responses. It looks like previous owner did more under my dash than I thought - the wire colors that plug into the factory tach aren't the same color as the wires that plug into the HEI cap. I guess I'll end up tracing the full run.
I probably should've known what I was getting into when I bought the car from a person who admitted to buying glass packs in 2004. "But it has the stock exhuast manifolds..." "Oh, I just thought it wasn't loud enough." The well-worn hunting knife I found under the seat pretty much confirmed everything I suspected.
I probably should've known what I was getting into when I bought the car from a person who admitted to buying glass packs in 2004. "But it has the stock exhuast manifolds..." "Oh, I just thought it wasn't loud enough." The well-worn hunting knife I found under the seat pretty much confirmed everything I suspected.
