Autometer Tach Wiring Question

[BigAL]

I have an Autometer 10,000 rpm tach and in the wiring instructions it says that for one of the terminals(3rd one in from the left in the diagram below) that it goes to a 12v Key On source or to the Dash Lighting Circuit. My question is does it matter which one you hook it up to, because one way would give it power when the key is on and the other way would do it when the dash lights are on. Also what is this wire for, as the lights for the gauge are wired separately.

And this is the Tach that I have.

http://www.autometer.com/5-tach-10-000-rpm-in-dash-elec-4243.html

[Deaf Bob]

If you wire it to the key, the light will be on all the time..
I do not even hook it up when checking the derby car..
No, I do not run a tach in the derby car..

[BangShift McT]

I have AutoMeter's NV tach, I spliced into the dash lighting wire at the switch so I only had backlighting when I needed it.

[anotheridiot]

back light only going on with dash lights and you should also get the dimmer to work as well if you wire it to the circuit.

[Loren]

Alex, I'm going to guess that the tach has internal circuitry that turns the back-lighting on only when the ignition switch is turned, regardless of if the light power supply is always on or not. A little different than what we're used to. So you could hook it to anything 12v+ (...and have the light be full-strength as it happens) or hook it into the dash lights as suggested and benefit from the dimmer feature.

[BigAL]

Alex, I'm going to guess that the tach has internal circuitry that turns the back-lighting on only when the ignition switch is turned, regardless of if the light power supply is always on or not. A little different than what we're used to. So you could hook it to anything 12v+ (...and have the light be full-strength as it happens) or hook it into the dash lights as suggested and benefit from the dimmer feature.

Thing is the back lights for the Tach aren't built into the Tach, they are separate and wired separately. Here's a pic of the back of the Tach, it's on the the left and as you can see there are two lights plugged into the back of it, they are the black plugs with the white and black wire coming off of them. So I'm wondering if the tach needle lights up and that is what that one terminal that goes to the lighting or 12v source is for?

[yellomalibu]

Wire it up either way, and find out. I like Loren's suggestion... if you can tap into a dash light wire, do it. It may give you dimming ability.

The way I wired up my tach umpteen years ago, I have no dimming - it's always bright.

[Loren]

Hmmm...I see what you mean. Weird...hafta just experiment I guess.

Hey do you want an assembly manual re-print for that truck (68-72)? I have one that may wind up being five pounds of paper in the recycle barrel if it doesn't find a home.

[STINEY]

Hmmm...I see what you mean. Weird...hafta just experiment I guess.

Hey do you want an assembly manual re-print for that truck (68-72)? I have one that may wind up being five pounds of paper in the recycle barrel if it doesn't find a home.

Calling second in line if BigAl passes on it.

[Loren]

He's got 'til tomorrow morning...

[oletrux4evr]

How's Gail doing?

[silver_bullet]

Thing is the back lights for the Tach aren't built into the Tach, they are separate and wired separately. Here's a pic of the back of the Tach, it's on the the left and as you can see there are two lights plugged into the back of it, they are the black plugs with the white and black wire coming off of them. So I'm wondering if the tach needle lights up and that is what that one terminal that goes to the lighting or 12v source is for?

I would tend to agree with this theory...

[BigAL]

Calling second in line if BigAl passes on it.

Go for it STINEY, Thanks for the offer Loren, but I won't need it.

[Loren]

Cool. I had a couple 67's for awhile with the usual plans until a bud came along and wanted them worse. The Green Machine, of course, looks bad-ass.

Stiney, pm me an address and I'll send it off this week.

Ed: All good, busy w/ work, dreaming of going out in the sailboat.

[Deaf Bob]

Good news on Gail! Miss her on here.. Give her a hug for me, I'm sure she won't want an actual one from me anyways!

On the light.. I say run it thru a dimmer switch! The kid's Powerstroke has a 3 guage pod on the windshield post.. It is hard to see out at night.. It is hooked up to be on when running.. Dark, low traffic roads are harder to see