Aftermarket Tach Guys get in here!

[BullittStangV8]

So i got my autometer tach with shiftlight in today. I ran the green (rpm trigger) wire to my msd box just fine. My question is this: Can I wire the wire thats suppose go to the light switch (I assume so that you can dim the tach lights), into a regular 12v power wire? Wouldnt this just make the tach background lights always be on when the car is on (Essentially the tach power and light wires would both be feeding off the same 12v power wire)? I dont mind that at all, as it would be allot easier then picking through the wires behind the dash. Finally, where do you guys ground out your wires in the dash area?
Thanks for answering such stupid questions...Im not an electrician..

 

[iskwezm]

my illumination wire is hooked to a 12V key switched and the ground is under the dash somewhere.

 

[Z06killinSBF]

I ran my illumination light into my fuse box and grounded under the dash some where.

 

[BullittStangV8]

So I can just grownd it to the actual dash..Are both of you guys tachs backlit all the time? The power is suppose to run off a switch 12V source I know, with a fuse in line. I was thinking of running the illumination off of the same power source wire?

 

[mustangman70]

Bullit you can do that!!


I Know this because i wired it up that way, mine stayed on all of the time because i hooked it together with thw 12v source wire...and i ran it without another fuse right out of the fuse box..Worked for years Only had to replace the bulb 2 or 3 times..

 

[BullittStangV8]

nice. I did a search (like I was supposed to) and found this link:

http://www.mustangforums.com/m_1546227/mpage_2/key_/tm.htm

The say that if the wire shown in the pic is light blue and has a red stripe, then its a dash light accessorie wire (it only has power when the dash lights are on). Anyone here agree with that? I checked under the dash, and mine is light blue with a red stripe. I think I could tap this, and the tach lights would turn on when the dash lights are on.
Also, my radio has a power wire (evidently for memory?) run from the starter selonoid, and is not fused...For some reason this scares me. Is it an issue? BTW the previous owner wired it up. Could I use this for a power sorce for the tach? Wouldn't that leave the tach on ALL the time? I was thinking of tappin the same wire which goes to the + coil as the source for driving the tach..

 

[mo'factor]

Gauges

I just replaced mine this summer, and I tapped the lt.blue/red stripe for illumination. I ran the power from the accessory jack, and grounded to the dash as everybody else did. There is another wire from the tach that has to go to the coil, but it different based on brand. I remember it was green on one of my previous tachometers. It is a bad idea to use any power source that isn't fused or protected in some other way.

 

[BullittStangV8]

ok im going to show just how much of a beginner I am at dash wiring...Wheres the accessory jack? I really just need a simple, easy wire to tap for on off 12v source..
The "coil" wire you mention for my tach is also green, and its wired to my MSD6AL box. My tach feed comes from there, not the coil. I'll throw a 10 amp fuse on that power wire tom I guess.

 

[mo'factor]

Accessory jack

The accesory jack I am talking about was a yellow connector that had three holes in it. It basically was a three to one splitter. You can tap off that wire if you prefer to do that. The wire I'm talking about went to the fusebox as an accessory. The Haynes or Chiltons guides can help you find out which wire that is for your year.

 

[dennis112]

I just replaced mine this summer, and I tapped the lt.blue/red stripe for illumination. I ran the power from the accessory jack, and grounded to the dash as everybody else did. There is another wire from the tach that has to go to the coil, but it different based on brand. I remember it was green on one of my previous tachometers. It is a bad idea to use any power source that isn't fused or protected in some other way.

This is the way I did it.

Blue/red strip for illumination. It will brighten and dim just like the gauge lights when the light switch is turned.
Yellow accessory plug for power.
For ground I used the existing location behind the dash gauge panel, it is a self tapping bolt that grounds the dash lights.

Here is my Autogauge tach with internal shift light mounted off center. With this arrangement I can easily see the speedo at lower to mid speeds (<100mph) and the amp gauge at all times.

 

[Z06killinSBF]

I pulled my gauge illumination fuse and got one of those fuse jumper things and run it from there. Only comes on when the lights are on so it aint getto wired. Werd

 

[palerider94]

On my 1970 there was a jack that came from factory that main purpose was to plug in additional stuff that can be dimmed with dash. I did not have to splice anything - just plug into jack when i did my oil gauge. I found out about it doing some research on mustang monthly - could not find write up running late for work but from what I remember it was suppose to be there for earlier models also. Many want to do some research on site before you splice wires. From what I remember it was a yellow jack.

 

[66Runt]

Tachometer installation

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[BullittStangV8]

I just saw that post. It solved my issues. I suggest its made a sticky, because it really is a step-by-step walkthrough that even idiots like myself can follow.

 

[66Runt]

I'd have to say, you have a high inteligence quotient

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[BullittStangV8]

Thanks for the encourangement Runt. Its frustrating asking such basic questions, when answers to them seem so basic im sure for allot of the more experienced builders/owners on the site.

Now. I have my tach wired up. BUT, I have 2/3 more guages to install over the next month. (fuel pressure/water temp/oil pressure). I know how to wire the sending units into the engine. But, the light dimmer/accessory 3 female jack under the dash by the pink resistor wire only has three plugs. One of them has my tach, leaving me with two more slots. Can I simply make another Y, and plug the male end into the jack, and the 2 female ends to the light wires from the guages? What about for the 12 V switched source that I have already Y'ed to power my guage, can I Y that out again to power more guages?

 

[19stang66]

ha i was going to mention those threads. glad you figured it out.

 

[66Runt]

That will work as long as you fuse your circuit

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